Best Oil For Generators 2020 – Top 6 Oils Reviewed

The Best oils for generators

In a hurry? Here are the best oils for generators on the market right now.

Best overall: Shell Rotella T6
“protects the engine from wear, deposits and oil breakdown.”

Most popular choice: Briggs & Stratton 30W
“It’s one of the most popular high-quality oils at the moment.”

Best premium choice: Generac Full Synthetic Motor Oil 5W-30
“It efficiently protects your engine against any sludge deposits and maintains its viscosity at low temperatures.”

Good in warm climates: Honda 08207-10W30
“It is a sound choice for homeowners who use generators in a warm climate”

Best for air-cooled engines: Briggs & Stratton SAE 5W-30
“gives maximum protection against wear, even when the conditions are severe.”

Very reliable: Cummins 3265336
“Another bonus of using it is that it lowers oil consumption of engines.”

Your generator might break down soon or be a hunk of an inefficient machine if the oil you feed it does not protect it against wear and tear and worsens its performance.

Many of us overlook the importance of the oil that goes into the generator. We often believe that the generator will work no matter what, even if its oil is not top quality.

However, the reality is that the oil is as crucial for the engine as the engine is for the generator. Thus, it is important that you buy a quality product to increase the life of your generator’s engine. Let’s look at some of the best oils in the market.

Best overall: Shell Rotella T6

Reasons to buy:

  • A lot of positive reviews
  • Great protection
  • Saves you money
  • Superb quality
Reasons not to buy:

As the name indicates, the Shell Rotella T6 is a full synthetic oil. The most noteworthy thing about this product is that it features a technology known as Triple Protection Plus, which protects the engine from wear, deposits and oil breakdown.

It saves the money which you would otherwise spend unnecessarily on fuel. That’s because it gives you better fuel economy. Besides, it maintains the efficiency of the fuel in the engine through its highly advanced formulation for low ash.

It keeps an optimal pressure in the engine of the equipment you are using. It also resists any loss of viscosity through shear. There are a number of vehicles which you can use it for such as vehicles driven on diesel including tractors, heavy pick-ups and cars.

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Most popular choice: Briggs & Stratton 30W

Reasons to buy:

  • Good for hot environments
  • High-quality oil
  • Great for 4-cycle engines
Reasons not to buy:

This oil by Briggs and Stratton has been designed to meet the needs of 4-cycle engines. It’s one of the most popular high-quality oils at the moment.

It is ideal for small engines. Briggs & Stratton has been in the business for a while now, and it won’t be wrong to say that they are experts when it comes to creating oils for smaller engines.

This oil keeps the engine running smoothly under demanding conditions. As its performance is truly remarkable, it makes it to the top of our list.

If you use generators or equipment in a warm temperature, this one is your best shot as it works exceptionally well in hot environments. Different oils work great in different conditions, so choose the one that works in the environment you happen to be in.

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Best premium choice: Generac Full Synthetic Motor Oil 5W-30

Reasons to buy:

  • Very high quality
  • Offers great protection
  • Exclusive oil
Reasons not to buy:

  • Pricey

The Generac Full Synthetic Motor Oil 5W-30 is modified and super distilled as it is a full synthetic motor oil. There are special additives in it to protect the generator when it hasn’t been used for a while. It is the best when it comes to quality, but it is also more expensive than most oils in the market.

However, that should not put you off from buying it as it will benefit the engine for the long run. Plus, you get more out of it than you invest in it. It efficiently protects your engine against any sludge deposits and maintains its viscosity at low temperatures.

If you also happen to be using a generator by Generac, this one is the best oil to go for.

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Good in warm climates: Honda 08207-10W30

Reasons to buy:

  • Great for warm weather
  • Protects the motor
  • Good quality
Reasons not to buy:

  • Not so good in cold climates
  • A bit pricey

Just like Briggs & Stratton, Honda is a trusted brand. People are quite familiar with its vehicles and similarly, its oils are popular as well. When used for Honda generators, this oil will make the engine run smoothly. You get top performance even when you use it for generators made by other companies. The American Petroleum Institute rates it as SJ, which means it is compatible with 4-cycle engines.

In addition to that, its viscosity rating shows that you can use it for environments that range from equatorial to temperate weather. However, it won’t work too well in cold conditions.

Another great thing about this oil is that it protects the motor against varnish deposits. Furthermore, it maintains viscosity throughout the year.

It is a sound choice for homeowners who use generators in a warm climate. Though it is a pricey product, it suits the needs of those who use a generator for equipment that run on small engines.

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Best for air-cooled engines: Briggs & Stratton SAE 5W-30

Reasons to buy:

  • Great for both cold and warm climates
  • Lowers oil consumption
  • Good for air-cooled engines
  • Very high quality
Reasons not to buy:

  • A bit expensive

Briggs & Stratton SAE 5W-30 is a synthetic oil. The good thing about this type of oil is that it gives maximum protection against wear, even when the conditions are severe.

Synthetic oils keep your engine functioning for a long time. Since the SAE 5W-30 is 100% synthetic, you don’t have to worry about its viscosity or about your engine breaking down anytime soon.

It gives the ultimate protection at all temperatures. It also improves starting as it lowers oil consumption.

It works well even when the conditions are extremely cold. Classified by the American Petroleum Institute as SJ/CD, this oil is perfect for equipment that run on air-cooled engines. It will work smoothly for almost any generator. Though it is a little expensive, the performance and quality you get from it will increase the life of your generator.

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Very reliable: Cummins 3265336

Reasons to buy:

  • Reliable
  • Good quality
  • Protective
  • The best for Cummins/Onan generators
Reasons not to buy:

  • Expensive

The company has been making efficient engines for a long time now, and its Cummins 3265336 oil does not disappoint when it comes to quality. It keeps engines running smoothly. Though it is a bit toward the pricey side, it is worth every penny.

The oil has been designed in a way to give your engine maximum protection. It is guaranteed to protect motor from wear and increase its life. Another bonus of using it is that it lowers oil consumption of engines.

Apart from that, it does an awesome job at reducing friction between the various components in an engine so that it keeps functioning properly for a long time. Cummins oils are thoroughly factory-tested to ensure that as you use them, they will be able to maintain the engine’s performance and not let it break down anytime soon.

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Buying Guide for Best Oils

Choosing a subpar oil can cost you more than you can possibly imagine. Therefore, it is vital that you never compromise on the quality of the oil. To help you make the best decision, we have compiled some of the features which you must look for as you buy an oil for your generator. We have also tried to answer some of the questions you might have.

Go Through the Owner’s Manual

Each generator comes with a manual that tells you what you need to know about the machine. Before you even think of buying an oil for it, read the manual carefully. It contains valuable information and will tell you which kind of oil you must use for the generator. Reading the manual of your generator should be the first step for buying an oil.

Viscosity of the Oil

The next thing you must focus on is the viscosity of the oil you are thinking of buying for your generator. The SAE 10W-30 is mostly used. SAE stands for Society of Automotive Engineers and references the rating system devised by the society. The rest of the code tells you the viscosity of the oil at different temperatures.

Let’s take SAE 10W-30 as an example. The 10W tells you how well this oil can be pumped when temperatures are low. The W here stands for winter. The second number indicates how well the oil can be pumped at a high temperature of 100 degrees Celsius or 212 degrees Fahrenheit.

Choose the Right Type of Oil

Always make sure you are using the right type of oil as mentioned in the user’s manual of the generator. If you use an oil other than the one recommended in the manual, there is a high chance that various parts of the engine might break down prematurely.

Keep the Environment in Mind

You need to keep the temperature of the generator’s surroundings in mind. Not all kinds of oils will work for your generator, especially if they aren’t meant for the kind of environment your generator works in. For instance, if you are using a generator in a very cold environment where temperatures are quite low, an oil with a rating of 5W-30 will be ideal for you.

Look at the Type of Engine

Knowing the engine type of your generator will greatly help you decide which oil will be the best one to buy. Basically, there are two types of engines which you will encounter: 4-stroke engines and 2-stroke engines.

Most generators have a 4-stroke engine. 2-stroke engines are not as common as the 4-stroke ones. Both these types of engines need different kinds of oil for their proper functioning, so you need to know your generator’s engine.

In a 2-stroke engine, you will have to use a mixture of engine oil and fuel. You can either mix them on your own or get a pre-mixed solution from the market. On the other hand, there is no need to form a fuel and engine oil mixture for the 4-stroke engine as you can pour them in separately.

Go for a Quality Product

It is recommended that you do not go for a cheaper product just to save a few bucks. If you use a low-quality oil for your generator’s engine, it will cost you more than you think you are saving. Try investing in a reliable product. Plus, it’s not like it’s a given that a high-quality oil will be expensive. Rather, there are many products which can be purchased at a reasonable price. Just make it a habit of not compromising on the quality of the oil just for the sake of price.

Can I Put Synthetic Oil in My Generator?

Yes, you can use synthetic oil for your generator. In fact, it’s even recommended to use it instead of any other type of oil. As opposed to the conventional oil, synthetic oil has more chemicals to improve its performance. It is more of a modified version of the conventional oil.

The higher process of distillation and refinement that it goes through allows it to give your engine the best protection. Besides, it has a higher viscosity, especially at extreme temperatures, which makes it much more suitable for using in cold conditions as well as in higher temperatures. It is most suitable for smaller engines.

The major downside of using synthetic oil is that it can blow a hole in your pocket since it is much more expensive than other types of oil. However, synthetic oils are more reliable and the performance they give you is unparalleled.

The best synthetic oil among the products we have reviewed above is the Briggs & Stratton 30W because it can work in the cold as well as in hotter climates.

Can You Use Motor Oil in a Generator?

Yes, you can use motor oil in a generator. In fact, you should put it in right when you get your equipment shipped because most manufacturers do not add motor oil to the engine before shipping. This oil will keep the engine lubricated so that it does not break down quickly. However, it is better to use synthetic oil in a generator because motor oil cannot match the performance or protection given by synthetic oil.


As manufacturers are employing several different advanced methods to make oils more efficient, there are a lot of options in the market these days. Out of all the different types of oils, synthetic oils are becoming more efficient to survive the competition.

You must prioritize buying a high-quality synthetic oil instead of buying just about any product you come across in the market. After all, if the oil you put into the engine gives a good performance, your generator would last for a longer time.

We have reviewed some of the best oils for generators. You can choose one based on the factors we detailed above.