Best engine oil for generators

Our Buying Guide gives you a detailed overview of the best oil for your generator. If you’re not sure which oil to use, don’t worry because this piece has covered you. Apart from the features and tips of the best oils, this article will also enlighten you about the best and most reliable oil brands available.

Best motor oil for generators

Best choice

Valvoline European Vehicle SAE 0W-40 Motor Oil

This is one of my favourites for use in extreme cold. As it is a fully synthetic small engine oil, it means that this Yamalube product keeps your engine clean longer. Most importantly, this plastic is rated by the API as having a viscosity of 0% by weight (0W), which means it flows immediately to all parts of the engine within the first few cranks after starting.

4,9 Rating
Faster oil flow when starting up
Helps maintain fuel efficiency

Best rated oils for generators

Top choice

Briggs & Stratton 30W Engine Oil

4,8 Rating
Warm weather formula for use in 40°-100° F temperatures
Warranty certified

Best choice

Valvoline European Vehicle SAE 0W-40 Motor Oil

4, 9 Rating
Faster oil flow when starting up
Helps maintain fuel efficiency


Honda Power Equipment SAE 10W30 Motor Oil

4,7 Rating
Well-known brand. Meets/exceeds SN API
Quick lubrication

Best oils for generator

The best oils for generators

Best rated oils for generator

1. Honda 08207-10W30 Motor Oil

2. Briggs & Stratton 30W Engine Oil – 48 Oz. 100028

3. Generac Full Synthetic Motor Oil 5W-30 SN Quart Bottle Part# 0J5140 (qt)

4. Cummins 3265336 Onan SAE 15W-40 Oil – 1 Quart

5. Briggs & Stratton SAE 5W-30 Synthetic Small Engine Motor Oil

6. Husqvarna XP 2 Stroke Oil 2.6 oz. Bottle 6-Pack

7. Valvoline Full Synthetic 0W-40

Synthetic oil for generators

The lights flicker during the storm, but you don’t even notice it. Finally, you have a generator for the backup.

But when was it last serviced?

You probably run your generator once a quarter and are religious about using fuel additives to stabilize the tank.
There are few tools you will buy in your life that are more practical than a portable gas generator. You are a saviour when the occasional storm turns off the power, and you can also make any camping holiday a much more enjoyable experience. Like any mechanical device, they require regular maintenance and must be kept in good working order. Do you need a new pipe wrench clone? So read a review 5 Best chic pipe wrench clones reviews 2019.

But what about the oil?

Whether you use a dedicated home standby generator or have portable generators that you want to use (my personal system), you want to invest in oil that can withstand the endless months of sitting and still protect the engine instantly the moment you need it.

If the backup power is needed, it is also likely that your generator engine will run continuously for several days. Is it ready for the job?

According to toolspost expert team, Shell Rotella T6 Full Synthetic Oil is the best oil for generators in 2019.

It is often overlooked that the most important moving part of any engine is its oil. Engines do not function without oil. When it comes to generators, it might be absolutely necessary to have the right oil and maintain it properly.

Generators are by definition important equipment; if you need one to pump heat, light and water, you really want to make sure your oil is up to date. When you need best synthetic oil for Toyota Corolla, read our review about this.

Different types of engines require different types of oil, and generators are special machines. If they are used with the right oil, they should never let you down.

Do you need a new oil for your generator but have no idea how to choose it? Then take a detailed look at our Buyer’s Guide. In addition to the tips and features you should be looking for, you will also learn more about the best and most reliable oil brands we recommend.

Our top picks of the best oils for generators

1. Honda 08207-10W30 Motor Oil

Buy Honda 08207-10W30 Motor Oil

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This high-quality engine oil is sold by Honda especially for use with its own products. It has Honda as original equipment manufacturer (OEM) on the bottle and is designed for Honda four-stroke engines used by generators, lawnmowers, scooters, go-karts and mopeds.

Therefore, it is strongly recommended to use this oil only if you have a Honda generator. It does its job when starting up, which is extremely important for two-stroke engines.

This oil will make your generator engine more efficient even if you use it as a refill solution for oil of a different specification. However, as far as the price is concerned, it is on the high side.


  • Well-known brand
  • Meets / exceeds SN API
  • Quick lubrication


  • A little pricey

2. Briggs & Stratton 30W Engine Oil – 48 Oz. 100028

Buy Briggs & Stratton 30W Engine Oil – 48 Oz. 100028

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From Briggs and Stratton comes the excellent engine oil that is perfect for generators. B & S are one of the best-known engine manufacturers in the USA and market oils that make their engines work better and last longer.

Fortunately for us this means that they also work excellently with other engines. This special mixed engine oil has some big advantages for generator engines.

It is a detergent oil, i.e. it keeps your engine clean by preventing the accumulation of waste products. Its formulation is designed to work best at high temperatures, such as those found in generator engines. It is also very inexpensive and comes in a convenient bottle.


  • Good for warmer temperatures
  • Warranty certified


  • A little expensive

3. Generac Full Synthetic Motor Oil 5W-30 SN Quart Bottle Part# 0J5140 (qt)

Buy Generac Full Synthetic Motor Oil 5W-30 SN Quart Bottle Part# 0J5140 (qt)

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Generac Power Systems is a leader in generator technology and this product is part of this process.

This is a synthetic oil that is becoming increasingly popular with users of high-temperature motors in general and generators in particular.

Traditional engine oil, refined from crude oil, changes over time and is exposed to heat. Basically, it gets thicker.
For a lubricating oil this of course poses massive problems. Thicker oil cannot move around the engine as intended, and your engine jams. If you have ever experienced this, you will appreciate the value of synthetic engine oil. This oil is fully synthetic and very valuable.


  • Created for generators
  • Exceeds highest API class
  • Protects against deposits


  • Too expensive

4. Cummins 3265336 Onan SAE 15W-40 Oil – 1 Quart

Buy Cummins 3265336 Onan SAE 15W-40 Oil – 1 Quart

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Cummins generators are highly regarded throughout the industry and their Onan brand is part of their reason to have such a good reputation. This one-quarter engine oil bottle has everything you would expect from such industry leaders.

Cummins use this oil for their own generator engines of a certain type, the type you and I use. The oil is tested in their own factories to make sure the engines work optimally.

It is designed for diesel engines, but also works excellently in gas-powered generators. It is designed to increase engine efficiency by resisting the viscosity caused by very hot engines.


  • Provides maximum protection for engines
  • Reduces consumption and engine wear
  • Factory tested oil


  • None

5. Briggs & Stratton SAE 5W-30 Synthetic Small Engine Motor Oil

Buy Briggs & Stratton SAE 5W-30 Synthetic Small Engine Motor Oil

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This excellent synthetic oil comes from Briggs and Stratton. It is designed for use in small four-stroke engines such as those found in some generators.

In addition to overcoming the viscosity problem of conventional engine oils, this is also a detergent oil that keeps the functional parts of your engine trouble-free. This is ideal for fuel efficiency and longer engine life.

Synthetic oil is also known for its ability to start working immediately after heating. Again, since the molecular structure does not need to heat up to lubricate properly, you can trust this oil in winter.


  • For Use In All Air Cooled 4-cycle Engines
    Use of synthetic oil does not alter required oil change intervals


  • Different oil types can work best at certain temperatures. Learn which one to choose for your climate.

6. Husqvarna XP 2 Stroke Oil 2.6 oz. Bottle 6-Pack

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Although the vast majority of generators used 4-stroke engines, there are some machines with “old-school” two-stroke engines. If you own one and need a new oil, choose Husqvarna XP+.

Husqvarna is a well-known manufacturer of small machines that use 2-stroke engines, so they have a lot of experience in formulating the right oil. This semi-synthetic oil is JASO-FD certified to meet the latest standards and requirements.

In addition, Husqvarna XP+ includes a fuel stabilizer and ensures low operating temperatures, resulting in better engine protection and less smoke. Fortunately, this oil is still on the affordable side.


  • Excellent for 2-cycle engines
  • Low operating temperatures
  • Low smoke formula


  • None

7. Valvoline Full Synthetic 0W-40

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This is one of my favourites for use in extreme cold. As it is a fully synthetic small engine oil, it means that this Yamalube product keeps your engine clean longer. Most importantly, this plastic is rated by the API as having a viscosity of 0% by weight (0W), which means it flows immediately to all parts of the engine within the first few cranks after starting.

This extremely low viscosity also has advantages in temperate climates. Even at room temperature, oil can start to thicken so that when someone starts his generator, there is a lot of slow-running oil that must first work through the engine before it heats up.

This means that your engine is not sufficiently protected in the first minutes of use, leading to problems with metal-to-metal performance.

This Yamalube oil does not have any of these problems, which means that the damage done to your engine during starting is significantly reduced.

In my opinion, however, this product is the best for areas with extreme weather conditions. You start at 0w for the fast coating properties and the faster flow, but then quickly move on to a 40 weight oil to improve protection under load and reduce oil consumption. (It is excellent for snow blowers).

It doesn’t have the brand awareness of Generac oil, but it is what I use in my standby generator (technically speaking, a portable generator I use when the power goes out).


  • Excellent engine cleanliness due to excellent sludge and paint protection
  • Excellent high temperature protection under tough driving conditions and superior cold protection through
  • faster oil flow when starting up
  • Helps maintain fuel efficiency
  • Fully compatible with all common and leading synthetic engine oils


  • Price is slightly too high

Quick Tips to Buy the Best Oil for Generators


As always, the first step in our Buying Guide is to take a look at the user manual or instruction manual you received with your generator. You will find any information you will ever need inside, so do not throw it away.

From your own experience, you will usually find information about the engine oil you need in the Maintenance section of your manual.


The most important feature to consider when selecting the engine oil for your generator is its viscosity. As mentioned above, you will find the recommended type in the Owner´s Guide or Manual.
In most cases you will need a SAE 10W-30.

The SAE refers to the rating system developed by the Society of Automotive Engineers. The rest of the code refers to the viscosity oil´s at different temperatures.

The first number in the code, in this case 10W, means how well this oil can be extracted at cold temperatures. The W refers to the word winter (not the weight). The second number in the code indicates how well the oil can be pumped when heated to 212 degrees Fahrenheit (100 degrees Celsius) or higher.

In addition, you should choose a high quality detergent oil with the service classifications SJ, SL, SM or SN of the American Petroleum Institute (API).

However, always check the correct type of oil in your instruction manual and do not rely solely on our recommendations. It may vary from one generator type to another. Filling in an oil other than the recommended one may cause premature wear of individual engine parts.


Another thing to consider when choosing the best oil for your generator is the temperature of the environment you will be using it. In fact, this has been highlighted in every single user manual we have seen.

If you will be using your generator in a very cold environment that only allows very low starting temperatures, a 5W-30 may be a better option for you. However, you must be aware that this oil is associated with increased engine oil consumption at higher operating temperatures, so check its level before each use.


Another thing you should consider before deciding what oil is good for your generator is to know what type of engine it is using. In our experience, there are only a small number of generators with a 2-stroke engine and a large majority of generators with a 4-stroke engine.

Each type requires a different type of engine oil.

While in a 4-stroke engine you use oil and fuel separately, in a 2-stroke engine you can either mix fuel and engine oil in a recommended ratio yourself or you can buy a premixed solution.


Finally yet importantly, you should never try to save engine oil for your generator. Favoring a lower price over a high quality product can lead to major concerns later on.

Rather, you should invest a little more in reliable brands, such as:

  • Honda
  • Onan
  • Briggs & Stratton
  • Mussel Rotella
  • Engine 1
  • Generic
  • Craftsman

The purchase of the right generator oil is crucial for the functioning of your engine. As we have seen, the generator manufacturers themselves produce oils that give their own products the best performance and longest life.

While these are some of the biggest names in the generator market, engine oil sold for use in these and other engines of similar size and speed may be derived from brand names more commonly associated with the automotive industry.

It is worth being careful. Choosing the wrong oil could be expensive and cost you more than money.

Here are some things to consider when choosing the engine oil for your generator:

Do you know your generator?

There is a wide range of power generators on the market, which makes the choice of oil more difficult than before. Largely, portable generators have been manufactured by certain companies to work with fairly normal oils;

Therefore, if yours breaks down at a campsite, you can probably borrow some from another friendly camper.
Today, generators are more readily available in manufacturing forms that require specific maintenance, including generator oil. Manufacturers will always recommend their own brand of engine oil;

However, it is still the case that other brands can function well. While the choice is greater, you can find a brand of oil on the market that actually has a better value.

Many people who rely on generators have the same for years and years. Reliability is by far the most important factor in usage.

This applies to the oil that keeps them running; and as the saying goes, if it is not broken, do not fix it. In today’s market this may not be such good advice. Do some research.

Real or synthetic?

This is a question that is often rightly asked when it comes to oil for generators. While the users of other engines may not have a choice for different applications, the increasing demand for synthetic lubricating oil often comes from the users of such small engines.

The main reason for this is the temperature these engines reach. Two-stroke engines rely on high temperatures to work efficiently, and traditionally generators have used them.

As we have seen in some of our reviews, synthetic engine oil is highly recommended for use in these engines, as it does not suffer from the problem of increased viscosity.

Synthetic oil is otherwise a consistent product; its price does not depend on that of a barrel of crude oil. Although it can be more expensive to bottle, its properties mean that it lasts longer than conventional engine oil. In the long run, this can save you money.

Of course, more oil that is powerful means a more powerful generator. This means less fuel, which is a consideration. Over time, synthetic oil will maintain your engine very well. Besides avoiding stalls and traffic jams, this can mean that you never have to buy a new generator.

It may not be at the top of the list, but there are also environmental aspects to burning fossil fuels. Apart from everything else, it will run out one day.

Can you use synthetic oil in a generator?

The short answer to this question is yes and is sometimes recommended. To understand why you first need to understand the differences between synthetic and conventional. Both types of oil initially come from the same place – the soil.

Synthetic differs in the higher process of refinement and distillation, where more chemicals are added to modify and improve the oils.

This process produces a cleaner oil that provides a much higher level of protection while at the same time providing higher performance, especially for smaller engines. This has to do with the overall higher viscosity at extreme temperatures – synthetic oils lubricate better in cold conditions or under high loads associated with high temperatures and dust.

The main disadvantage of using synthetic small engine oils is that they are hard on the handbag. But for reliable backup performance and durability, these plastics are unbeatable.

In addition, the maintenance schedule of your generator can be extended, resulting in less downtime for power tool repairs.

How often should I change the generator oil?

Generator oil filters and oil filters should be changed every 100 hours of generator life. With synthetic oil this time can be doubled to 200 hours.

In the event of a longer power failure, i.e. approximately every eight days. By comparison, most lawnmowers recommend changing the oil once every 50 hours. If in doubt, remember that an engine has never been worn out by too many oil changes. As a side note, most lawn mower manufacturers recommend changing the oil filter and air filter once every two oil changes.


Q: What are the different groups of base oils or synthetic oils?

Synthetic oils fall into different categories from Group 1 to Group 5, which differ in their performance, although you can expect Groups 5 and 4 to provide the best performance. The rest of the groups then follow, with Group 1 being the lowest, followed by Group 2, then Group 3.

Q: How much oil should I expect my generator to consume?

Basically, there is nothing like a standard amount of oil that you should expect generators to consume. The reason for this is the number of variables that affect the amount of oil you should expect a generator to consume. These variables include the model, engine hours, load and other factors. It is therefore up to you to check your oil tank to ensure that the generator is in good condition.

Q: What type of generator oil is suitable for my engine?

Different engine types require different types of generator oils, with 7kW, 12kW and 15kW air-cooled generators requiring 10W-30 for temperatures above 20°F and 5W-20 or 5W-30 for temperatures below 20°F. However, you can use 5W-30 synthetic oil all year round after the first oil change.

On the other hand, liquid-cooled units require 15W-40 oil. You should ensure that this oil is SAE compliant and meets the requirements of API service class SF for gasoline engines. One point to note is that if you have an engine that has been previously serviced with conventional oil, then you should top it up with the same type and avoid mixing it with synthetic oils as this can damage the engine.

Q: What happens if I put too much or too little oil in my generator?

If you add too much oil, the resistance of the engine may increase and even cause the oil to leak from the air filter. On the other hand, too little oil is consumed quickly, which activates the oil warning system to prevent the engine from burning. Therefore, it is important that you fill in the correct amount of oil based on the instruction manual.

Q: Should I top up or replace the oil in my generator?

While you can choose to top up your engine, it is best to change the oil so that you can extend the life of the engine. The reason for this is that the oil deteriorates over time due to high engine temperatures, resulting in a reduction in efficiency. So choose replacement, not refilling.

Concluding remarks

As the technology advances, we will have more choices. This applies to generator oil as well as everything else mechanical. Just to drive the point home, engine oil is a part of your engine.

As technology advances, synthetic oils become cheaper and can compete better with the old type.

For such a cheap product, it is worth thinking about what you are actually buying. For many people, engine oil is an afterthought; think about fuel, etc., until their generator stops working.

Don’t be fooled by the fact that all oils are the same. There is a reason why they have our recommendations for the best oils for generators. They are all made to high standards, and that’s because they really know which products are healthy for small engines. When you buy oil for your generator, you can’t do anything wrong by using one of the oils tested here.

We hope that our guide to the best generator oils will help you make the right choice.

Best Oils for Generators in 2020 – Reviews and Buying Guide 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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