Chainsaw Oil: How to Choose the Right Oil for Your Chainsaw

By Paige Cerulli

Updated on Sep. 26, 2024

Chainsaw oils are essential to keeping your chainsaw running well. Understanding the different types of oils can help you choose the right one.

Just like your car’s engine depends on oil to keep it running smoothly, your gas-powered chainsaw engine needs oil to operate at its best. Different chainsaws require different oils, and using the wrong oil or not enough oil can cause major problems.

Knowing the available chainsaw oil options, learning how to choose the right one and determining the right fuel/oil ratio can help ensure your chainsaw runs smoothly every time.

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According to Nancy Egelhoff of Egelhoff Lawnmower Service, Inc., oil keeps a gas-powered chainsaw engine’s parts moving smoothly. “If you don’t have oil, you could destroy the engine,” she says. “If there’s no oil in the cylinder and piston of the engine, it will heat up so badly that it will score the cylinder and piston, and you will ruin the saw.”

Egelhoff says the damage might not be immediate. Some customers have seen damage occur as much as six months after they’ve forgotten to put oil in their chainsaw.

Chainsaw engine oil can go bad. Two-cycle oil is good for up to five years when sealed, and many manufacturers list the oil’s shelf life on the container. Once opened, that oil will only have a shelf life of two years.

When you open a container, record the date on the container so you can throw out the oil if it’s not used within two years. Exposing oil to drastic temperature changes and moisture can also make it go bad.

Here’s what can happen if you use bad oil in a chainsaw:

When shopping for chainsaw engine oil, you may notice that some brands cost more than others. While this oil is all basically the same, Egelhoff highlights the importance of buying a product you can trust. If you see a real deal on engine oil that’s much less expensive than name-brand oil, it could be a lower quality product.

“If it’s an off-brand, you don’t know where it’s made, and the manufacturer might not back their product,” she says.

When choosing chainsaw engine oil, you’ll need to know if you have a two-cycle or four-cycle engine.

With a four-cycle engine, you’ll put oil and gas into separate reservoirs. Four-stroke oil goes in four-cycle engines. It contains special additives and base oils that support the stages of the four-stroke engine (the intake, compression, power and exhaust stroke).

For a two-cycle engine, you must mix gas and oil together in a specific ratio. Old chainsaws, manufactured prior to 2003, require a 32:1 ratio. Chainsaws manufactured after 2002 usually require a 40:1 or 50:1 ratio. Check the two-cycle engine housing to see if it specifies the appropriate ratio. If you can’t find it there, refer to the owner’s manual.

Vince Christofora, owner of Woodstock Hardware in Woodstock, New York offers this advice. “One thing we do for our customers who buy a chainsaw that requires an oil/gas mix is we have them buy a gas can and we write the formula right on the can with a big black Sharpie. Then, the next time they need to make the mixture, they can dump in the right amount of oil and take the can to the gas station and pump in the right amount of gas.”

Here’s what can go wrong if you don’t have the right gas-to-oil ratio:

To simplify things and avoid the whole gas-to-oil ratio issue, Egelhoff says many of her customers buy Stihl MotoMix, a premixed fuel/oil product.

“There are several things that make this a brilliant product,” she says. “There’s no ethanol, and that’s the worst thing for small engines since it deteriorates lines, loses its spark very quickly and can separate out so you’re introducing both water and gas into the engine.” Stihl MotoMix has a two-year shelf life.

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If your chainsaw has a two-cycle engine and you’ve properly mixed the gas and oil, checking your oil is as simple as verifying you have plenty of the gas mixture in the tank.

“Some chainsaws have a translucent tank so you can easily see the level of the gas mixture in the fuel tank,” Christofora says. “For those that do not, add some fuel and then check the fuel level by looking in the tank opening. If you are doing a small job a half a tank of fuel will be more than enough. If you have a big job or long day ahead of you, you may want to fill the tank right to the top.”

If your chainsaw has a four-cycle engine, you’ll need check the oil with the dipstick:

The exact steps to take when changing your chainsaw fuel/oil will depend on the model, but the following steps outline the general process:

If you’re working with a four-cycle engine, you will need to change the oil because it’s separate from the gas:

It’s always wise to refer to your owner’s manual for details and directions specific to your chainsaw.

Besides chainsaw engine oil, you’ll also need to keep your chainsaw supplied with bar-and-chain oil. This helps keep the chain lubricated, makes it easier to cut and helps keep your chainsaw from wearing out quickly.

Bar-and-chain oil comes in two types: summer and winter. Egelhoff explains that summer and winter oils have different viscosity. Winter oil is thinner, allowing it to run smoothly even in cold temperatures and when stored for awhile. Summer oil is thicker, heavier and formulated to work in hot conditions.

A chainsaw uses bar-and-chain oil as it runs, and you’ll need to add about one tank of this each time you go through a tank of fuel. It’s easiest to keep up with your bar-and -chain oil by filling the reservoir every time you fill up the fuel tank. Many chainsaws have a bar-and-chain oil reservoir with a level gauge that lets you see how much oil is in the reservoir.

Note: Biodegradable, biobased, chainsaw oils (bar-and-chain and engine oils) have become popular in recent years because of the environmental impact of petroleum-based oil products. Consider these more earth-friendly products when buying oil for your chainsaw.