Manual transmission fluid

Transmission oil is a mixture of base oil and additives with very good anti-wear and anti-scoring properties and good stability against thermal oxidation. Manual transmissions use a variety of oils: normal engine oil, heavy hypoid transmission oil or in some cases even automatic transmission oil. Refer to your gearbox manual to find out what your gearbox needs.

Best manual transmission fluid

Best choice

Mobil 1 Synthetic Gear Lube 75W-90

Mobil 1 Synthetic Gear Lube LS 75W-90 is a premium quality, multi-purpose synthetic automotive transmission lubricant designed to meet the highest performance requirements of modern passenger cars under all operating conditions, including limited slip applications, while providing superior power transmission performance.

  • 4,9 Rating
  • Excellent rust, pickling and corrosion protection of copper and its alloys
  • Excellent performance with limited glide

Top rated manual transmission fluid

Top choice

Red Line API GL-4 SAE 75W80

  • 4,8 Rating
  • For GL-1, GL-3 & GL-4 applications
  • MLT transmission oil with balanced friction control

Best choice

Mobil 1 Synthetic Gear Lube 75W-90

  • 4, 9 Rating
  • Excellent rust, pickling and corrosion protection of copper and its alloys
  • Excellent performance with limited glide

Recommended

Royal Purple ROY MAX GEAR 75w-140

  • 4,7 Rating
  • Specially designed to extend the life of gears and bearings
  • Superior corrosion protection

Best Manual Transmission Gear Oil

Manual Transmission Fluid

Best Synthetic Transmission Fluid

1. Red Line MT-90 75W-90 GL-4

2. Genuine Ford Fluid XT-75W90-QGT SAE 75W-90

3. Lucas Oil LUC10047 Clear Gear Oil

4. Mobil 1 104361 75W-90 Synthetic Gear Lube

5. Valvoline High Performance SAE 75W-90 Conventional Gear Oil

6. Red Line 75W90 Synthetic Gear Oil

7. Royal Purple ROY01300 Max Gear 75W90 Synthetic Lube

8. Liqui Moly 20012 SAE 75W-90 GL-4 Gear Oil

Best 75w90 Gear Oil

1. ACDelco 10-4016 75W-90 Synthetic Axle Gear Oil

2. Valvoline SAE 75W-90 Full Synthetic Gear Oil

3. Liqui Moly SAE 75W-90 Fully Synthetic Gear Oil

4. TriboDyn 75w90 Synthetic Gear Oil

5. AMSOIL FULL SYNTHETIC Severe Gear Lube 75W-90

6. Castrol Syntrax Limited Slip Gear Oil – 75W-90

7. RAVENOL J1C1109 SAE 75W-90 Gear Oil

Best 75W-80 Gear Oil

1. Red Line SAE 75W80 API GL-4

2. Genuine Mitsubishi 75w-80

3. Quicksilver Premium Gear Lube 80W-90

Best 75w140 Synthetic Gear Oil

1. Ford Genuine Fluid Synthetic Rear Axle Lubricant 75W-140

2. Amsoil Severe Gear SAE 75W140

3. TriboDyn 75W140 Full Synthetic Gear Oil

4. Lucas 75w-140 Synthetic Gear Oil

5. Royal Purple ROY MAX GEAR 75w-140

6. Red Line 75W-140 Gear Oil

7. Valvoline SAE 75W-140 Full Synthetic Gear Oil

Best transmission fluid 75W-90 GL-4

1. Red Line MT-90 75W-90 GL-4

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75W90 GL-4 Transmission oil (similar to SAE 5W40/10W40 engine oil viscosity). Popular for Nissan, Mazda, Mitsubishi, VW/Audi, Lotus Elise/Exige, Toyota, Mendeola transmissions and Atlas transfer cases for Off Road. Offers faster shifting and a perfect synchronizer friction coefficient. Safe for brass synchronizers, as it lacks the reactive sulfur that is found in most GL-5 oils and causes damage. High performance gearbox protection and longer synchronizer life. Eliminates gritty shifting, even in cold conditions. Meets transmission oil viscosity requirements of 75W90, 80W90, 90 and engine oil viscosity of SAE 40, 10W40 and 15W40. Recommended for GL-1, GL-3 and GL-4 applications and where most special synchronizer fluids are specified.

Pros:

  • Less slippery low sulphur formula compatible with brass synchronizers
  • Stable at high temperatures in power applications
  • Also available as lighter viscosity like MTL and MT-85

Cons:

  • The bottle is too small

2. Genuine Ford Fluid XT-75W90-QGT SAE 75W-90

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Motorcraft SAE 75W-90 Premium Synthetic Transaxle Lubricant is a high quality lubricant recommended by Ford Motor Company for use in the Ford GT transaxle. It provides excellent shifting and synchronization performance even at low temperatures.

Pros:

  • It offers excellent switching and synchronization performance
  • Works even at low temperatures
  • It provides complete lubrication for reduced wear
  • This fluid is compatible with other synthetic and conventional mineral oil axle lubricants.
  • Formulated for automotive applications

Cons:

  • Difficult to find in the store

3. Lucas Oil LUC10047 Clear Gear Oil

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Lucas SAE 75W-90 Synthetic Gear Oil is a non-foaming, super-smooth, long-life lubricant designed specifically for heavy-duty or high performance applications where other gear lubricants are simply not good enough. It contains a special additive package that dampens gears and prevents leakage under extreme pressure situations where other gear lubricants are simply not good enough. Specially designed to withstand high temperatures without losing its lubricity.

Pros:

  • Heavy duty use
  • High performance
  • Withstands high temperatures

Cons:

  • None

4. Mobil 1 104361 75W-90 Synthetic Gear Lube

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Mobil 1 Synthetic Gear Lube LS 75W-90 is a premium quality, multi-purpose synthetic automotive transmission lubricant designed to meet the highest performance requirements of modern passenger cars under all operating conditions, including limited slip applications, while providing superior power transmission performance. Compared to conventional hypoid gear lubricants, Mobil 1 Synthetic Gear Lube LS 75W-90 performs exceptionally well over a wide temperature range. This is achieved through a unique proprietary formulation that provides optimized viscosity as a function of temperature characteristics along with the highest level of inherent formulation stability, protecting against thermal and oxidative degradation, wear and corrosion, and viscosity loss associated with premature shear. It can also be used for prolonged operation and to support fuel economy. It contains special friction modifiers designed for differentials with limited slip. In most applications, the addition of special LS (Limited Slip) additives is not required as they reduce wear and chipping at high speeds, high torque and high power in racing and high performance vehicles.

Pros:

  • Exceptional thermal stability and resistance to high temperature oxidation
  • Excellent protection against wear at low speeds or high torque and scoring at high speeds with the ability to handle the toughest driving conditions while delivering smooth, efficient and reliable performance
  • Maintains viscosity and film strength under severe operating conditions to prevent wear
  • Excellent rust, pickling and corrosion protection of copper and its alloys
  • Excellent performance with limited glide

Cons:

  • Not good to have that in the primary

5. Valvoline High Performance SAE 75W-90 Conventional Gear Oil

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Valvoline’s high performance gear oil is a thermally stable extreme pressure gear lubricant that can withstand severe temperatures and shock loads while providing excellent wear, seizure and corrosion protection. It is recommended for all hypoid differentials (conventional and limited slip) and manual transmissions in passenger cars, light trucks, SUVs, vans and heavy trucks where API GL5 or MT-1 fluid is required. Excellent for high speed, high torque and high power.

Pros:

  • Protects against high temperatures to extend service life
  • Formulated with extreme pressure additives to minimize gear wear under shock loads
  • Helps protect against gear wear caused by galling, chafing, corrosion and pitting
  • Recommended for locking hypoid differentials and non-synchronized manual transmissions in passenger cars, light trucks, off-road vehicles, vans and heavy trucks for which an API GL5 or GL4 fluid is mandatory.

Cons:

  • The gear feels really rough and is not so smooth

6. Red Line 75W90 Synthetic Gear Oil

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Red Line’s 75W90 synthetic gear oil is their most popular gear oil and the preferred product in almost all car and light truck differentials, both conventional and sliding. 75W90 is preferred for most racing applications. It contains a friction modifier, which is recommended for limited slip differentials. 75W90 transmission oil can be used in many transmissions and transaxles. Exceeds API GL-5, Red Line synthetic transmission oils are designed to provide the highest level of protection and efficiency for your powertrain. Red Line offers a complete line of powertrain lubricants optimized for use in differentials, transmissions, or transaxles over a wide temperature range. The right choice depends on the manufacturer’s requirements and whether the application is for passenger cars, commercial vehicles or racing. Red Line transmission oils contain polyol ester basestocks to ensure excellent lubrication even under extreme conditions with high loads and high temperatures. Their natural lubricating properties provide excellent glide, reducing sliding friction in hypoid gears to reduce wear and temperatures.

Pros:

  • Enables faster shifting
  • Makes the transmission synchronizers faster to equal speeds
  • Can also be used in racing differentials with limited slip

Cons:

  • Too thick

7. Royal Purple ROY01300 Max Gear 75W90 Synthetic Lube

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Max-Gear is an extremely resistant automotive gear oil. It is designed to maximize performance and provide unsurpassed protection for heavily loaded transmissions. It ensures that transmissions run smoother, quieter, cooler and longer without overhaul. Max-Gear outperforms other gear oils by combining the highest quality synthetic oils with Royal Purple’s patented Snarled additive technology. Max-Gear is recommended for use in truck, RV/RV and car front or rear differentials, manual transmissions and lower transmissions of marine engines, which require the use of an API GL-5 or GL-4 fluid. All Max-Gear viscosities are formulated with hypoid friction modifiers required for use in clutch or cone differentials. No additional additives are required.

Pros:

  • Provides maximum protection to heavily loaded gears
  • Max Gear outperforms ordinary gear oils by combining the highest quality synthetic oils with Royal Purple’s proprietary Synerlec additive technology
  • Max Gear ensures that gears run smoother, quieter, cooler and longer without overhaul

Cons:

  • None

8. Liqui Moly 20012 SAE 75W-90 GL-4 Gear Oil

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Liqui Moly’s SAE 75W-90 hypoid transmission oil is a full synthetic, top-quality, high-pressure transmission oil for heavy-duty manual, auxiliary, transaxle and hypoid transmissions where an API GL 4+ lubricant is required. High-quality oil on a synthetic basis and modern additive technology guarantee a wide range of applications and optimum transmission lubrication under extreme conditions. The low viscosity of this transmission oil also makes it suitable where shifting problems exist. (e.g. stiffness or noise development). Promotes easier shifting and quieter running. With excellent protection against wear and corrosion. Guarantees a considerable reduction in noise. Suitable for use with long oil change intervals. For manual gearboxes of passenger cars, modern transaxle drives. Mainly in transmissions of VW and numerous other vehicle manufacturers.

Pros:

  • Excellent aging resistance, good viscosity/temperature properties
  • Reduces transmission noise, wide viscosity range
  • Excellent wear protection, high rust and corrosion protection
  • Low manual switching effort, optimum pressure absorption capacity
  • Good seal compatibility

Cons:

  • None

Best synthetic transmission fluid

75W90

1. ACDelco 10-4016 75W-90 Synthetic Axle Gear Oil

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ACDelco Synthetic Axle Lubricant GL-5 (75W-90) is a high performance lubricant for GL-5 axles at extreme temperatures and pressures. It resists the high temperatures encountered during extended high-speed operation and heavy towing, while maintaining excellent flowability in cold temperatures. The full synthetic formulation of ACDelco Synthetic Axle Lubricant GL-5 (75W-90) provides oxidation and thermal stability. This product combines long fluid life with a pleasant grape fragrance.

Pros:

  • Improved formula contains a grape fragrance for a more pleasant application experience
  • Meets the GL-5 specification of the American Petroleum Institute (API) for use under severe conditions
  • High quality formula designed to withstand high temperatures encountered during extended high speed operation while maintaining flowability at cold temperatures

Cons:

  • Didn’t have much of a grape smell

2. Valvoline SAE 75W-90 Full Synthetic Gear Oil

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Valvoline SynPower Gear Oil is a superior sulfur-phosphorus extreme pressure gear lubricant formulated with synthetic raw materials and additives to provide excellent performance. It is designed to provide excellent extreme pressure protection, excellent load carrying capacity, low foaming performance, excellent corrosion protection and excellent thermal stability protection. It is recommended for conventional and high performance applications. Valvoline SynPower transmission oil is recommended for use in axle applications requiring factory filled or drained and filled levels with limited slip performance. Valvoline SynPower gear oil is recommended for use in axle applications requiring limited slip by filling or draining and filling at the factory.

Pros:

  • Formulated to maintain excellent protection of liquids at low temperatures
  • Provides excellent thermal stability for cleanliness and longer life
  • Contains special additives that help protect gear teeth from rust and corrosion and reduce the rattling of locking differentials.

Cons:

  • Hard pressing out the oil

3. Liqui Moly SAE 75W-90 Fully Synthetic Gear Oil

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Full synthetic gear oil. Ensures exact friction behavior and offers excellent ageing resistance. Even under the most difficult conditions and with large temperature fluctuations, it guarantees perfect functioning of the unit. Highest lubrication reliability, maximum wear protection due to wide range of viscosity. Enables easy shifting and extremely quiet running.

Pros:

  • For manual transmissions, transaxles, rear axles, hypoid gears
  • Offers superior wear protection and significant noise reduction
  • For easier shifting and quieter operation

Cons:

  • None

4. TriboDyn 75w90 Synthetic Gear Oil

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The patented synthetic TriboDyn gear oils are 100% synthetic, superior base oils formulated into a complex blend of extreme pressure lubricants in combination with high performance coating technology designed to minimize friction and wear, increase gear and bearing life, reduce operating temperature under extreme heat and pressure, and provide extreme shock and high load protection. This unique formula also ensures continuous performance by dispersing and holding on to critical areas without creating resistance, providing benefits in both start-up and continuous performance while protecting against corrosion. The proprietary technology is a smart material that is attracted to areas of heat and friction. As pressures increase with speed or load, the specialty lubricants, combined with active coating technology in the oil, can form a self-lubricating ceramic film in areas of high load and heat. This provides critical protection that actively identifies areas that require increased lubrication, and sometimes not only reduces or eliminates wear but can also repair damaged surfaces.

Pros:

  • Full synthetic base oil of highest quality is improved by patented TriboDyn additives
  • Users report lower transmission temperatures – smoother shifting – significantly reduced wear
  • Additives help to bind oil on metal surfaces without increasing the resistance = better starting protection
  • Provides protection against extreme shocks and high loads

Cons:

  • Difficult to find in the store

5. AMSOIL FULL SYNTHETIC Severe Gear Lube 75W-90

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Severe Gear Synthetic Extreme Pressure (EP) Gear Lube is a premium gear oil specially formulated for maximum performance in heavy-duty applications. This state-of-the-art formulation features an exclusive blend of high viscosity, shear stable synthetic base oils and an additional treatment of high performance additives. Severe Gear Synthetic EP Gear Lube retains its viscosity to provide long-lasting protection against metal-to-metal contact. The proprietary additives form an iron sulfide barrier coating on gear surfaces, providing the ultimate line of defense against wear, pitting and scoring. Severe Gear helps prevent “thermal leakage” – a phenomenon caused by the inability of a lubricant to control friction and increased heat under high load conditions.

Pros:

  • Superior film strength
  • Controls thermal runaway
  • Rust and corrosion protection
  • Helps to reduce the operating temperatures
  • Maximum efficiency
  • Long life of oil, seals and equipment

Cons:

  • Pricey

6. Castrol Syntrax Limited Slip Gear Oil – 75W-90

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High-quality full synthetic gear oil. Provides maximum wear protection under heavy duty operating conditions and during prolonged draining. Improved thermal stability and excellent shear stability for outstanding wear protection. Meets or exceeds the requirements of API GL-5 and MT-1

Pros:

  • Very good flow properties at low temperatures, i.e. fast grease supply to the components and low friction losses.
  • High temperature stability combined with excellent wear and noise protection during operation.
  • Low foaming tendency, especially at high speeds.
  • High shear stability in conjunction with excellent wear protection, even under extreme conditions with extreme oil temperatures.
  • Low transmission oil temperature, high comfort and long service life.

Cons:

  • None

7. RAVENOL J1C1109 SAE 75W-90 Gear Oil

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RAVENOL VSG SAE 75W-90 is ideal for use in highly stressed axle drives. RAVENOL VSG SAE 75W-90 is suitable for synchronized and non-synchronized manual gearboxes, transfer cases and auxiliary gearboxes requiring API GL-5 or GL-4 oil.

High additive reserves for extended oil change intervals according to manufacturer specifications. Excellent cold flow properties. Best wear protection and best transmission efficiency. Fuel savings even over short distances at low outside temperatures. Stable lubricating film even under heavy loads. Exceptional corrosion protection and good compatibility with non-ferrous metals.

Pros:

  • Specially developed transmission oil of German manufacture for use in synchronized and non-synchronized manual transmissions, transfer cases and auxiliary transmissions which require API GL-5 or GL-4 oil
  • Ensures trouble-free transmission and differential function with excellent wear protection and transmission efficiency
  • Offers increased fuel efficiency even over short distances and low outside temperatures
  • Suitable for use in Mercedes-Benz, ZF, Volvo, BOT, BMW and more according to the specifications listed in the following description

Cons:

  • The bottle and its unique cap are not easy to handle.

Best MTL 75w80 GL-4 Gear Oil

1. Red Line SAE 75W80 API GL-4

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Lubricant for the 70W80 GL-4 manual transmission, which offers faster gear changes, an improved friction coefficient and better protection of the transmission. It also provides better cold gear changes and works on both high and low mileage vehicles. SINCE 1979 In 1979 Red Line Synthetic Oil began manufacturing lubricants for the racing industry. TECHNOLOGY Red Line responds to the technical challenges of today’s performance industry with state-of-the-art technology. Red Line’s products are more powerful and protect better than anyone else in the market. No compromises.

Pros:

  • High performance transmission protection, meets the requirements for transmission oil viscosity of 75W, 80W and engine oil viscosity of SAE 30, 10W30, 5W30
  • MLT transmission oil with balanced friction control for most manual transmission synchronizers
  • Because it lacks the reactive sulfur that is found in most GL-5 oils and causes damage. Recommended for GL-1, GL-3 & GL-4 applications
  • Founded in 1979, Red Line Products offers more performance and protection than any other product on the market

Cons:

  • Pricey

2. Genuine Mitsubishi 75w-80

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Oil for mechanical transmissions of Mitsubishi cars. The fluid is recommended for a manual gearbox, providing a gentle change of gears at different temperatures.

Pros:

  • Genuine Mitsubishi products for your car
  • One quarter container
  • Fits: eclipse 2000 – 2012, Lancer 2003 – 2017 EXCEPTION EVO 6 speed & SST, Outlander 2003 – 2006,
  • Outlander Sport 2011 – 2018, Mirage 1997 – 2002, Mirage 2014 – 2018

Cons:

  • Price is slightly too high

3. Quicksilver Premium Gear Lube 80W-90

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The Quicksilver brand has been a leader in supplying uncompromising engine oils, parts and accessories to the marine industry for over 65 years. Quicksilver is the leading supplier of Mercury engine parts, oils and accessories for the marine industry, as well as all brands of original equipment in the marine and motorsport industries. The company has built a loyal following by supplying the highest quality products, tested through some of the most rigorous environments and test procedures. No aftermarket company can match the level of research and design that Quicksilver has achieved; buying Quicksilver means buying performance, protection and peace of mind.

Pros:

  • Formulated to protect against corrosion and excessive wear
  • Improved emulsifiers protect gears in case water enters the gear housing
  • Special additives protect gears from metal-to-metal contact. Exclusive formulation helps to improve adhesion of the film to gear wheels

Cons:

  • No high output

Best 75w140 synthetic gear oil

1. Ford Genuine Fluid Synthetic Rear Axle Lubricant 75W-140

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Motorcraft SAE 75W-140 Synthetic Rear Axle Lubricant is manufactured using high quality synthetic base oils and performance additives to provide improved thermal and oxidative high temperature stability. It helps to reduce operating temperatures. It has improved wear protection for hypoid wheels, excellent shear stability and protects against rust and corrosion. This product meets all Ford Motor Company’s durability requirements.

Pros:

  • Distinguishes itself by its excellent resistance to high temperatures
  • Minimizes wear and tear and extends the trouble-free life of the transmission
  • Stability over a wide temperature range
  • Reliably protects against rust
  • Compatible with all gaskets and seals, does not damage them
  • It is an original product made by Ford concern

Cons:

  • Quite expensive

2. Amsoil Severe Gear SAE 75W140

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AMSOIL Severe Gear Synthetic Extreme Pressure (EP) Lubricant SAE 75W-140 gear oil is used for light, medium and heavy-duty trucks, buses, special equipment, 4X4 SUVs, tractors, racing cars, tractors and residential vehicles.

Pros:

  • Superior film strength
  • Control of thermal outliers
  • Rust and corrosion protection
  • Reduced operating temperatures
  • Improved efficiency
  • Longer life of oil, seals and equipment

Cons:

  • None

3. TriboDyn 75W140 Full Synthetic Gear Oil

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The patented synthetic TriboDyn gear oils are 100% synthetic, superior base oils formulated into a complex blend of extreme pressure lubricants, combined with high performance coating technology designed to minimize friction and wear, increase gear and bearing life, reduce operating temperature under extreme heat and pressure, and provide extreme shock and high load protection.

Recommended for all road, truck and off-road vehicles, including all forms of high-performance racing, as well as other stationary and mobile equipment. Specially designed for use in differentials, manual transmissions, worm gears, power dividers, compressors, oil lubricated wheel bearings, transfer cases, pumps and all transmissions.

Pros:

  • Attraction of heat for the lubrication of areas with high friction
  • Minimize friction and wear
  • Reduce operating temperature
  • Provides protection against extreme shocks and high loads

Cons:

  • None

4. Lucas 75w-140 Synthetic Gear Oil

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Lucas 75/140 Synthetic Gear Oil is a super-smooth, long-lasting lubricant designed specifically for heavy duty or high performance applications where conventional gear lubricants are simply not good enough. They contain a special additive package that increases lubricity and ensures less gear noise and longer bearing life. Excellent for use in limited slip differentials. Designed to withstand high temperatures without losing its lubricity.

Pros:

  • Super smooth, long lasting lubricant
  • Contain a special additive package that increases lubricity
  • Designed to withstand high temperatures without losing its lubricity

Cons:

  • None

5. Royal Purple ROY MAX GEAR 75w-140

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Max Gear ensures that gears run smoother, quieter, cooler and longer without overhaul. A direct reduction in drag in the powertrain has a huge advantage for trucks and other four-wheel drive vehicles: better gas mileage. Max Gear is formulated with a friction modifier additive – no additional additives are required.

Pros:

  • Specially designed to extend the life of gears and bearings
  • Superior corrosion protection
  • Maximum protection for heavily loaded transmissions while maximizing power throughout the powertrain

Cons:

  • You may notice slight vibrations from the rear end

6. Red Line 75W-140 Gear Oil

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Red Line’s 75W140 synthetic gear oil is a GL-5 rated product recommended for road vehicle differentials where this viscosity is specified and offers excellent performance in both conventional and limited slip units. It is popular in the rear differentials of the latest generation of Ford trucks and many other popular models. Red Line synthetic transmission oils are designed to provide the highest level of protection and efficiency for your powertrain. Red Line offers a complete line of powertrain lubricants optimized for use in differentials, transmissions or transaxles over a wide temperature range.

Pros:

  • Recommended for road driven vehicles
  • Good slid ability and synchro-compatibility
  • Offers excellent performance
  • Additional protection of the equipment

Cons:

  • None

7. Valvoline SAE 75W-140 Full Synthetic Gear Oil

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Full synthetic Valvoline SynPower transmission oil is designed for ultimate protection and performance. A thermally stable extreme pressure transmission lubricant functions and protects in both high and low extreme temperature conditions. SynPower Gear Oil is specifically recommended for ratchet hypoid differentials and is compatible with conventional gear lubricants.

Pros:

  • Formulated to maintain excellent protection of liquids at low temperatures
  • Provides excellent thermal stability for cleanliness and longer life
  • Contains special additives that help protect gear teeth from rust and corrosion and reduce the rattling of locking differentials
  • Recommended for conventional and limited slip differentials and non-synchronized manual transmissions where API GL-5 or API GL-4 fluid is specified

Cons:

  • None

What does the transmission oil do?

The key function of transmission oil is the lubrication of hypoid gears in manual and automatic transmissions for cars and trucks.

When should the transmission fluid be checked?

It is important to check the transmission fluid level regularly between maintenance intervals. If you let your car drive with little transmission fluid, the transmission may shift incorrectly or not at all. It can also damage the internal parts of your transmission that are not lubricated properly. Unfortunately, you may not hear any noise or have other indications that your transmission is low on fluid until it is too late.

How can the fluid level of the manual transmission be checked?

Checking the transmission fluid is actually not that easy: the transmission is not easily accessible without equipment, and there is no simple system – such as an engine oil gauge – to determine the oil level.

Checking the transmission fluid level requires working under the hood of the car with the engine running. This can be very dangerous if you are not careful. Contact your car mechanic to have the oil level checked. He has equipment for checking the oil level and topping up oil if necessary.

However, if you still wish to carry out this operation yourself, here is our advice:

Before starting to check the transmission oil:

  • Get a cloth or a roll of paper towel.
  • Refer to your service manual to find out what transmission fluid your transmission needs and how often it should be changed. In this manual, you will also find the location of the fuel filler cap.

Where is the dipstick for the transmission fluid?

On some cars, the transmission dipstick can easily be confused with the crankcase oil dipstick, so you should be aware of the location of your transmission. Look towards the back of the engine, near the firewall. In front-wheel drive cars, the transmission dipstick is normally located at the front of the engine, connected to the transaxle.

Lucas oil stabilizer in manual transmission

You can mix Lucas Oil Stabilizer 25% / 75% in a manual gearbox and 50% / 50% in the differential. Lucas Oil Stabilizer can be mixed with any petroleum-based or synthetic oil and is formulated for petrol or diesel engines.

Lucas Transmission Fix is a solvent-free formula that prevents slippage, hesitation and rough shifting on worn out transmissions and completely eliminates most seal leaks. Use in any transmission for preventive maintenance. Also in light manual transmissions to increase shifting comfort and transmission life.

Manual transmission oil type

Transmission fluid is a slippery fluid that acts as a lubricant for all moving parts inside your transmission. In an automatic transmission, this fluid also serves as a coolant and viscous fluid that transfers power from the engine to the transmission.

Different fluids are used for different transmissions. Automatic transmissions use something that – shockingly – is called automatic transmission fluid. Manual transmissions use a variety of oils: normal engine oil, heavy hypoid transmission oil or in some cases even automatic transmission oil. Refer to your gearbox manual to find out what your gearbox needs.

Should I do this service when it is recommended?

Yes, definitely, regardless of whether you have a manual or automatic transmission.

Manual: Most manufacturers recommend that the manual transmission fluid should be changed every 30,000 to 60,000 miles. For heavy-duty use, some manufacturers suggest changing the transmission fluid every 15,000 miles.

Automatic: The service intervals for an automatic transmission vary from every 30,000 miles … until never. The typical service interval is 60,000 to 100,000 miles. Changing more often does not hurt.

Why do I have to do this?

Manual: With a manual transmission, the problem is not so much the deterioration of the fluid, but rather the contamination of the fluid. This contamination occurs over time as the synchronizers, bearings and gears in the transmission wear out. The resulting metal particles then float around in the lubricant. In addition, we all know that oil with microscopic metal particles in it does not lubricate as well as clean oil. Therefore, if these contaminants are not drained off, they shorten the life of your gearbox.

Automatic: Because more heat is generated in an automatic transmission, automatic transmission oil actually breaks down and decomposes during use.
In addition, as with a manual transmission, the automatic transmission fluid is also contaminated by worn parts of the transmission. If these contaminants are not drained, they will shorten the life of your transmission.

Best gear oil for manual transmission

An oil’s use can be determined by the SAE number or grade it is assigned. Numbers of 60 and higher indicate gear oil while lower numbers indicate engine oil. This means 75w90 and 80w90 are both gear oil.

75w-90 Transmission Fluid

The 75w90 gear oil is used under extreme pressure conditions and is recommended for limited-slip differentials and for use in colder climates. Used in heavy duty manual transmissions, final drives and axles, high temperatures will not effect the heavy film left by this oil. Accordingly with SAE, oils are divided into types depending on the viscosity index.

The decoding of the 75w90 oil is as follows:

  • 75w – indicates how fluid the oil is in cold conditions. The smaller the number in front of the letter, the greater the fluidity of the oil. The minimum temperature limit is minus forty degrees;
  • 90 – characterizes viscosity at high temperatures.

The maximum temperature limit is plus thirty-five degrees.

In temperate climates, it is advisable to choose greases such as 75w85, 80w90, 75w90. For hot conditions, the use of 75w140 oils is optimal.

80w-90 Transmission Fluid

The 80w90 gear oil can be used in extreme pressure conditions and as a lubricant for non-synchronized manual transmissions in heavy duty trucks or buses. This gear oil is recommended for conventional and limited slip differentials.

The decoding of the universal oil 80w90 is as follows:

  • 80 – the minimum temperature limit is minus twenty-six degrees;
  • 90 – the maximum temperature limit is plus thirty-five degrees.

80w90 grease is considered quite popular today, it copes with the load and cold conditions.

Information on which type of motor oil is recommended for use in certain vehicles is prescribed in the operating manual.

What Is the Difference Between 75w-90 vs 80w-90 Gear Oil?

75w90 is synthetic and mostly superior to 80w90, but it costs more. 75w90 has better low temperature viscosity and it is fine to run it throughout. If you’re in a place that does not get very cold, there will be little advantage running 75w90 and in theory, 80w90 may even be more shear stable.

What Is the Difference Between 75w-90 vs 75w-140 Gear Oil?

75W-140 is SAE viscosity designation, however if you open the standard you will not see such a record there, but you will see separately 75W and 140. This inscription on oil means that it is universal and can be used both in winter and in summer, and the temperature range of its use will depend on 75W standards in winter and 140 in summer.

There is a big difference between 75w90 and 75w140 weight oils.

If dealership says to use 75W140 oil but not 75W90. This means that oil won’t be as thick and will not lubircate as well when it gets hot. Use whats reccommended unless you feel like shelling out the money for a new rear axle.

75w-140 oil is a high quality transmission lubricant used in heavy duty units.

Depending on the scope of use, oils are divided into types that reflect the technical characteristics and the possibility of application in any unit.

best gear oil for manual transmission

What is the difference between gl-4 and gl-5 gear oil?

Many users are wondering: what is the difference between transmission oils of API GL-4 and API GL-5 standards? In addition, often manufacturers of lubricants indicate on their products compliance with both standards at the same time – API GL-4/5.

  • API GL-4 is defined for gear oils used for bevel and hypoid gears of gearboxes and drive axle units operating at moderate speeds and loads.
  • API GL-5 is for high-speed hypoid gears and drive axles operating at high temperatures and subject to short-term shock loads.

GL-5 oil is recommended for heavier gears (e.g. hypoid gears), as well as universal for most mechanical transmissions that do not have non-ferrous alloy synchronizers in their construction.

This is due to the fact that the EP package contains sulfur-phosphorus elements that can cause corrosion of non-ferrous alloy parts.

Thus, GL-4 is typically used for synchronized gearboxes, and GL-5 for axles and gearboxes. For front-wheel drive cars, as Corrosion control of synchronizers can go against the protection of final drive gears, because they are in the same block. Just remember that GL-4 and GL-5 are gear oil ratings, not transmission oil ratings.

Between 75w90 motor oils from different manufacturers there is a difference both in characteristics and in cost.

Usually this oil product is synthetics. Sometimes manufacturers write on the canister that it is a semi-synthetic gear oil. From synthetic it has only one difference, which consists in a small content of filler substances.

Transmission Fluid Video

David Muench (Carnes Mechanical)

David Muench (Carnes Mechanical)

Hey, I’m David. I’ve worked in a cars store for 6 years. I write reviews and guides, helping people to choose the most suitable technicals and best product for them. I’m happy to finally share my knowledge of the industry here, on CarnesMechanical.

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