What Kind Of Oil Does A Generator Use?

There are different types of generators. They vary in size, type of fuel used, power output, and usage. Different type of generator requires different types of oil. So, what kind of oil does a generator use?

Types Of Generators

Putting Oil In A Generator With A Funnel
Photo: GeneratorPick

There are different types of generators. They vary in their recommended usage, power output, and type of fuel use. Below are different types of generators that are commonly used at home, RVs, and commercial establishments. 

Portable Generators

Portable generators are fuel-powered. They are very compact, easy to move around, and need no professional installation. Portable generators are widely used in RVs, homes, commercial establishments, and pop-up shops. Because they have smaller power output than standby generators, portable generators can only power small appliances, electronics, and mobile devices.

Inverter Generators

Inverter generators are just like the usual generators but with electrical components. They produce clean energy and are more suitable for electronic devices, such as laptops and smartphones. Inverter generators are portable and easy to maintain.

Standby Generators

These are generators that are installed in homes and commercial buildings permanently. They automatically turn on when there is a power outage. Since they have bigger power output, standby generators can power the entire building during emergencies and natural disasters.  

Now that you know the common types of generators, let’s learn what kind of oil does a generator used in the next sections. 

Champion Portable Generator On A Construction Site
Photo: GeneratorGrid

Importance Of Oil For Generators

Before we look deeper into what kind of oil does a generator use, let’s first understand the reasons why oils are important. 


No matter what kind of oil does a generator use, one of its purposes is to provide lubrication. 

The engine of the generator creates a lot of friction with other internal parts. This friction will turn into heat. As the speed increases, more and more friction is produced. The engine oil you use for your generator will provide lubrication and, as a result, prevent overheating. 

Rust and Corrosion-free Functioning

As you use the generator over a long period of time, internal parts will produce oxides which can cause corrosion. To prevent this from happening, you need to apply the appropriate engine oil. No matter what kind of oil does a generator use, engine oils contain special additives that prevent the engine from corrosion, rust, and other damage.

Cleaning and Maintenance

When the generator is used for a long time, carbon residues are produced. These residues are present in the engine and other internal parts, which will affect the performance of the generator is remains unattended. It can cause extra fuel consumption, detonation, and damage to the engine. 

Engine oil, no matter what kind of oil does a generator use, has a clean dispersion function that prevents the accumulation of residues.

You have the option to pick what kind of oil does a generator use. Whether you use the most expensive or the cheapest ones, you still get the same benefits. However, for maximum results, it is always best to use the engine oil that is suitable or recommended for your generator.

Choosing The Right Oil For Your Generator

Not sure what kind of oil does a generator use? Here are a few important things to remember when choosing the right oil for your generator:

Checking Generator Oil Level With A Dipstick
Photo: Wikimedia

Read the Manual

The first thing you need to do if you want to know what kind of oil does a generator use is to read the operator’s manual. The manual will help guide you on what oil best works for your generator. It will help you how to operate the generator, from break-in period to cleaning and maintenance. To know what kind of oil and how much oil you need, refer to the maintenance section of your operator’s manual.

Determine the Engine Type

There are different types of generators, and they are equipped with different types of engines. Different engine types require different oil types. Generally, generators are using SAE 10W-30 engine oil. This type of oil is recommended for hot weather but can also be used in cold weather. The SAE 10W-30 engine oil ensures smooth and flawless operation.

Check the Oil Viscosity

Viscosity is one of the important features that you need to look into if you want to determine what kind of oil does a generator use. Viscosity refers to the oil’s level of resistance to flow and shear. There are different things that affect viscosity – level of water, level of particles, and the overall age and shape of the engine. 

The viscosity of the oil is not so hard to determine when you are buying the right engine oil for your generator. You can easily find the viscosity in the name of the oil itself. Here’s how you:

The first number before the letter “W”, which stands for winter, is the viscosity of the oil at 0 Fahrenheit. The second number refers to the value at 212F. Thus, for hot temperatures, the higher the second number is, the better. 

Consider the Temperature

As mentioned before, temperature affects the viscosity of the oil. Thus, it is another feature that you need to consider when buying oil for your generator. 

If you want to use a generator that can withstand low temperatures below freezing, you need the type of oil that can keep up with your needs. For example, if you need your generator to perform at temperatures as low as -22 degrees Celsius, then you will need the 5W-30. 

SAE ClassificationTemperature (Fahrenheit)
The temperature range that the oil functions (lubricates) optimally
SAE 5W-20-37⁰ to 77⁰
SAE 5W-30-22⁰ to 86⁰
SAE 10W-30-20⁰ to 96⁰
SAE 10W-40-15⁰ to 100⁰
SAE 15W-30-13⁰ to 95⁰

Use Oils from Reliable brands

If you want your generator to perform well and last longer, buy engine oils only from trusted brands. Make sure the oil is approved by the Society of Automotive Engineers (SAE). It is recommended to use engine oil with high-quality certification and performance levels.

Standard vs Synthetic Oils

Synthetic oils are made from petroleum molecules. One of the characteristics of synthetic oil is that it contains fewer contaminants. It is formulated to prevent sludge and other contaminant build-ups. 

Synthetic oils have a higher viscosity index. They are also more efficient in terms of energy, and they improve generator maintenance. All in all, synthetic oils will cost you more, but they offer greater benefits than standard engine oils.

Now that you already know the important tips in choosing the right oil for your generator, have you decided yet on what kind of oil does a generator use?

How To Change Oil In A Generator

Aside from knowing what kind of oil does a generator use, it is also important to know how to change the oil of a generator. Here’s a simple guide:

Changing The Oil On A Generator
Photo: GeneratorPick
  • Heat up the old oil inside the engine. This will help to easily drain out the oil.
  • Place the generator on blocks that give enough free space under the oil drain plug. 
  • Unplug the spark wire. Grab the spark wire boot firmly and then twist it in either direction while pulling it off at the same time.
  • Remove the oil plug and drain the old oil in a draining pan. 
  • Replace the old oil filter. This will help prolong the life of your generator.
  • Reinstall the oil drain plug and then pour the new oil. Use a funnel to make refilling easier.
  • Reconnect the spark plug wire. Run the generator for a couple of minutes to let the clean oil move and lubricate the engine.


What kind of oil does a generator use?

Always purchase oil brands that meet the SAE (Society of Automotive Engineers) standards. Remember, the colder the weather, the smaller the number should be. For above 32°F, use SAE 30; below 40°F, and down to -10°F, use 10W-30. The Synthetic 5W-30 is good for any temperature. 
So, when it comes to choosing the best oil for your generator, make sure to use the recommended oil by your operator’s manual and the outside temperature where your generator is running.

Can I use normal oil in a generator?

It is fine to use a 5W-30 rated oil in a colder climate. However, if you are running your generator at a warmer temperature, it is recommended to use a 10W or 15W rated oil.

What kind of oil do you use in a gasoline generator?

It is recommended to check your owner’s manual to determine the right oil to use in your generator engine. Gasoline generators have internal combustion engines that need cooling and enough lubrication. Based on viscosity and outside temperature, a 10W-30 rated oil is best for temperatures from -20⁰ to 96⁰.

It is suitable to use 5W-30 oil in my generator?

If you are running your generator in a colder climate, using 5W-30 rated engine oil is acceptable. If you are in a warmer climate, it would be better to use 10W or 15W rated oil. Always remember, that the lower the first number is, the more fluid the oil is.

Can I use SAE 30 instead of 10W-30 in my generator?

Refer to your generator owner’s manual to know the recommended engine oil for your generator. The SAE 30 oil, commonly used in seasonal engines like lawn mowers, is also known as monograde oil. If you are running the generator above 32°F, use SAE 30. If it is below 40°F and down to -10°F, use 10W-30 engine oil. For all temperatures, use a synthetic 5W-30.

When is the perfect time to change the oil of my generator?

Refer to the generator owner’s manual for the recommended schedule on when to change your generator oil. In general, it is recommended to change oil between 100 to 150 hours of use. Always follow the schedule to avoid sludge and other buildups that can cause damage to the engine and other internal parts.

Can I use synthetic oil in my generator?

In general, the answer is yes. Synthetic oils are thinner and are formulated to benefit engines. However, it is always advisable to refer to the owner’s manual for recommendations.

What is the best oil for my generator?

There are different types of generator engines, and there are also different types of oil, depending on the temperature and viscosity. Generally, you can use SAE 10W-30. However, if you are in a warmer climate, you can use SAE 30. If you want a more flexible type of oil that works well with warm and cold weather, use the synthetic 5W-30-rated oil. Always do an oil change in your generator between 100 to 150 hours of run time.

Can I use 10W-30 in my generator?

For most types of generators, 5W-30 and 10W-30 are fine. The 5W-30 engine oil is more fluid at a lower temperature. You can also use either synthetic oil or mineral. If you are not sure what kind of oil does a generator use, refer to your owner’s manual.

How often should I change generator oil?

Generally, it is recommended to perform a full oil change between 100 to 150 hours of use. This is highly important if you are running your generator on a regular basis and for a long period of time. When changing the oil from your generator, make sure to allow the generator to cool off before adding the new oil into the engine. If you are unsure about what type of oil to use and how often you should change oil, then refer to your owner’s manual.


If you want your generator to last longer and perform better, it is recommended to get the right engine oil. It will help the engine produce less friction and have a corrosion-free operation. Finding the right engine is not hard; you just need to learn what type of engine your generator has and what oil to use.

There are different types of oil for generators. Just remember to consider the engine type, oil viscosity, and temperature. If you are not sure what kind of oil does a generator use, it is recommended to refer to the operator’s manual. 

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I'm Wayne. I have worked in the construction industry for many decades and have had the opportunity to work with various equipment and portable generators. I've also written extensively about both subjects. I spend time with my family when I'm not writing or working in construction.

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