10 Of the Best Oils for Use With Generators

When your generator starts getting old, or you open a new one, you will have to add the right oil to ensure everything is lubricated and running smoothly. Knowing which oils are the best can be a big challenge, especially as the choices you have to make become more complex.

You can usually find the best oil for your generator listed in the user manual. If your generator’s brand makes a generator oil, that is often the best and most reliable option. For most generators, high-quality semi-synthetic oil is good. It’s reasonably priced and can withstand most temperatures.

It can still be challenging knowing which oils will work with your generator as it may not be a brand-new generator. It is essential to learn how to choose an oil for your generator, how much it needs, the best oils, and the overall best way to ensure your generator has enough.

How Do You Know Which Oil Will Work with a Generator?

A new generator will have the oil types that work with it listed inside the manual, usually having a preferred code of quality that you can purchase. Older generators will require that you search the model of the engine up through a dealership, with most manufacturers having a backlog.

Many older generators will not have manuals anymore because they get lost as people sell and resell the machine, with most owners not always keeping track as needed. However, generator engines rarely change, so it’s often relatively easy to find the right oil for your machine.

However, we recommend still talking to a professional who can accurately determine what types of oils are needed. If you speak to a technician at most shops that sells oil, they can access a database that will tell you which oils work well with your generator.

What Are the Best Oils for Generators?

We have worked with many generators that have stopped working because the oil was wrong; we recommend understanding which ones are the best for your specific unit. Further, many new oils will have chemical parts that you can use in older generators without a problem.

It is important to note that oils will help make your generator run well when it is brand new, oils that will work better on well-run machines, and oil for old generators. Knowing which oils are suitable for 2-stroke engines or help to move pistons is essential.

  • Castrol 03084 EDGE: A full synthetic oil is easily one of the most common oils that you can find on the market, allowing you to run your generator comfortably. At only around $40 for one quart, one bottle will easily refill your generator, allowing you to run it with ease.
  • Shell Rotella 550045347: Around $25 for one quart, the Shell T6 is also a fully synthetic oil used in most gas engine generators. We recommend using this if you are unsure about which oil for your generator will work the best.
  • Pennzoil Ultra Platinum: At around $60, this is one of the more expensive oils on our list of recommended oils for your generator. However, because of the nature of this oil, it can comfortably last a lot longer than your normal oils would last, no matter the temperature.
  • Valvoline Premium Blue Extreme: Diesel generators need more specialized oils as the engines are much more sensitive to the wrong fluids and filters. At around $40, this oil will work with most diesel generators to keep them going and happy throughout the year as you may need to use them.
  • Generac Full Synthetic Oil: Generac has a line of oil for their generators that allows you to easily service and maintain them. Usually, around $70 for one quart of oil, you will comfortably use this on your Generac generator without having to stress about whether to oil is right or not.
  • Schaeffer 9003D-012S Supreme: This synthetic oil can handle extremely low temperatures and extremely high temperatures with ease for smaller engines. Usually, around $50 for a quart, you can comfortably service your portable generator with one or two quarts without stressing.
  • Echo 6450001 Power Blend 1 Gallon Oil Mix: Aimed at 2-stroke generators, the Gulf Universal 2-stroke oil will comfortably have your small generator running with ease. Because of the large amount of oil needed to run a 2-stroke engine, the price of 1 gallon of oil is only around $14.
  • AmazonBasics Full Synthetic Motor Oil: When you are never sure about where to go or need something delivered fast, we recommend the Amazon Basics. While we would recommend getting proper oil, at around $60, it is not the cheapest but will run the generator perfectly.
  • Castrol 03093 GTX: At 5 quarts, this is the most common brand of oil that you can buy at shops around the world. We recommend buying these a bit more pricey when you know your generator will need to be serviced a lot more often, at a price of around $90 for the full 5 quarts.
  • Honda 08207-10W30 Motor Oil: A shocking amount of generators use Honda engines to power your home. This is the best oil to use for most Honda generators as the formula helps keep everything running smoothly at around $60 for a quart.

Why Should You Use Specific Oils for a Generator?

Generators need specific types of generators to allow everything to work correctly, with the oil filter, the lubrication level, and the generator heat requiring specific oils. If you use the wrong type of oil in your generator, it may overheat and cause the pistons to seize as the machine starts to work.

We always recommend using the precise oil recommended for your generator because the generator may become entirely inoperable if you are not using the right oil. Often, fixing all the issues caused when you use the wrong oil will cost more than the generator is worth fixing.

While you don’t always have to use the exact oil, as oil quality changes over time, we recommend that you always stick to the closest possible match. This is often why the older a generator is, the more likely it is to use full synthetic oil, as these are the only ones that do what is needed.

Can You Use Synthetic Oil in a Generator?

Yes, most generators are perfectly fine running synthetic oil as these oils are suitable for a much broader range of uses than organic oil. Because you may have to replace the oil in a generator, we recommend using less expensive synthetic oils anyway to help maintain costs.

Synthetic oils are pretty adaptable and usable in a wide variety of situations. This is why you will find that people will supply you with an all-purpose synthetic oil when you are unsure what your generator needs.

Unlike in the past, where synthetic oils were not as good, modern oils are usually synthetic, especially for engines. The generators that you are using to power your home will be the same and enjoys the synthetic oil just as much as any other engine that needs good lubrication will need.

How Much Oil Will a Generator Usually Need?

This depends heavily on the type of generator you have; a small portable one you can lift with one hand will not need more than a quart. However, larger, permanent generators can easily need well over 10 quarts of oil to be filled, with some need even more.

Generally, people recommend buying a 5 quart can of oil to ensure that your generator will have enough to fill both the oil pan and the engine block. You should not fill the oil in your generator to the brim, instead just enough to ensure that the catch hooks on the bottom of the pistons can catch it.

Many people assume that everything is submerged in oil when the engine is working; however, this is not true as the engine’s bottom moving parts instead capture the oil. It throws it onto the engine parts that need the oil while the pistons are splattered with the oil as they move.

Can You Use Car Oil in Your Generator?

If you have both a gas car and a gas generator, you can use the same oil for both machines in most cases. However, we recommend that you have different bottles as the oil you use for your car will be significantly more.

Your car generally uses a lot more oil when it needs to be refilled, meaning that you may not have enough if you are constantly servicing the generator. Many people happily have bought several bottles of oil in the preparation of servicing their car, using a few liters to reoil their generators.

Usually ending up with not nearly enough oil for their car as the generator used slightly more than expected. While you may not need to use the generator without oil, you will have to use your car to go and buy more oil when you have run out of oil.

Which Types of Oil for a Generator Will Work Best in Hot Weather?

All-purpose oils will usually work the best when you live somewhere the weather is always hot, as they are supposed to reach extremely high temperatures. Many generator owners have their machines outside in the wind and rain, where the sun can bake their machine when they need to use it.

Most synthetic oils are all-purpose oils that will work wonderfully in these conditions and allow your machine to stay perfectly lubricated without the oil becoming liquid. What usually happens is that the oil overheats and stops doing what it needs to do when you have the wrong oil.

If the engine heats the oil beyond what it can handle, you need to replace the oil entirely, as the heat causes a chemical reaction. This is why we always recommend that you have all-purpose oil that can handle the heat to ensure the best possible protection for your machine.

Which Types of Oil for a Generator Will Work Best in Cold Weather?

While an all-purpose synthetic oil will work, we recommend getting something silicone-based when you live somewhere the temperatures reach well below freezing. When a normal oil freezes, it can cause massive damage to the insides of your generator or engine, which costs more to fix.

Oils made for extreme colds have extremely low freezing points, allowing them to work even when the temperatures reach well below freezing. However, these oils can still become sludge-like, which is why you should have a way to heat the generator before starting it.

Many modern generators made to run in cold environments do not have heating coils built-in. These coils will turn on and ensure that the oil inside is hot enough for everything to move freely without working against easily frozen or sludge-like oil inside the machine.

Are There Different Types Of Oil for Different Generators?

The oil you use for a gas generator will not work for a diesel generator, as the components and needs of the engines are completely different. Further, you cannot use regular motor oil for a 2-stroke engine, as these engines physically burn the oil along with the fuel.

If you use the wrong type of oil in your generator, it can cause a lot of damage and lead to you needing to replace the engine. Many people have had their engines completely seized when they get the wrong types of oil in the engine and cause them to become completely useless.

We would recommend not using the generator when you are unsure about the type of oil it currently has in it. Choosing the right oil will help your generator last a lot longer, or you can choose the wrong oil to have to replace a generator that you only bought a few days ago.


When you need to choose the right oil for your generator, we recommend that you always go with the recommended oil for your generator. Without the right oil, your generator will not be able to run smoothly, eventually burning out and becoming almost entirely unusable.

Whatever you do, please don’t think that your generator will work fine without any oil at all; no one wants a welded shut engine!


Hubert Miles

I've been conducting home inspections since 2002. I'm a licensed Home Inspector, Certified Master Inspector (CMI), and an FHA 203k Consultant. I started PickGenerators.com to help people better understand whole-house and portable generators.

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