What is the best oil for a chainsaw engine fuel mix?

Saturday, December 2, 2023

Choosing the best chainsaw engine oil for fuel mixtures 


Just like a car engine needs the right engine oil, and your lawnmower too, your chainsaw will benefit from using the correct engine oil too.

In case it's not clear, we are talking about the kind of oil you mix with petrol before you add it to your two-stroke engine not oil for the chain bar!

Chainsaw engines are smaller than lawnmowers and of course cars, so run differently - at different speeds, different accelerations and at different temperatures.

If you want to ensure your chainsaw engine is properly maintained, then you need to use oil designed for use in a chainsaw.

best chainsaw engine oil

When filling a small engine such as a chainsaw with fuel, it's quite likely to be a 'two cycle' or two-stroke engine. This means the fuel added will be a mixture of gas petrol and oil, usually in a 50 to 1 ratio of gas to oil.

Do not add car engine or lawn mower oil to your chainsaw fuel! 


The quality of petrol and oil used is quite important to the proper running and life of the engine.

Unsuitable fuels or mix ratios that do not suit the manufacturer's design and intended use of the machine can cause damage to the engine which can include piston seizing and excessive wear. Gaskets, fuel lines and the fuel tank itself could be damaged if the incorrect oil is used.

It should now be clear that you should only ever use 2-cycle engine oil with your chainsaw*. Anything else will probably wreck it so, no you cannot put ordinary car oil in it!

What kind of oil to use? You'd be pretty safe with any of the major brands such as Husqvarna or Stihl.

*Can I use synthetic oil in my chainsaw fuel?


Just like their use in lawnmowers, synthetic oils have been demonstrated to have superior combustion characteristics over mineral oils on top of delivering great lubrication on chainsaw engines.

Synthetic oils will leave you with a much cleaner engine. They usually also have additives like octane enhancers, detergents and stabilizers to help burn cleaner than other engine oils. This means they will cause much less smoke as well.

You can also use semi-synthetics which cost less than fully synthetic oils. They still have fine combustion properties and give you better lubrication than you’d get from standard mineral oil.

Pros of using synthetic chainsaw oil

  • Will lubricate better than standard oil
  • Less coating on the piston and in the crankcase
  • Leaves your engine cleaner, produces less smoke exhaust

Cons of using synthetic oil


Here is some popular brand options for which it is hard to go wrong on choice!

How to mix gas and oil for a chainsaw

Before fueling the chainsaw, clean the fuel cap and the area around it to ensure that no dirt or wood chips fall into the fuel tank.

Have your oil and gas ready. You may wish to have a high-octane gas.

Have your chopper positioned so that the cap points upwards.  

In order to reduce the risk of fuel coming in direct contact with skin and inhaling fuel vapour, remove the fuel cap carefully so as to allow any pressure build-up in the tank to release slowly. 

Your container for mixing should be clean, free of dirt and debris and one that is actually designed for holding fuel.

Pour the oil into the canister first and then add the gasoline or petrol. Make sure you get the ratios right by using the measured marks on your container.  

Close the canister and shake it vigorously to ensure proper mixing of the oil with the fuel.

Then pour the mix into your chainsaw. 

Close the caps firmly and place your saw upright. You are ready to rock and roll.

Time to think about chainsaw safety eh?

How long can I store mixed gas and oil fuel?

It's recommended that you only mix enough fuel for the activity for which you are about to undertake. 

The mixture will deteriorate over time which makes engine performance suffer and even make it hard to start chainsaws (so you can remove fuel from your machine when storing if you wish to avoid that). 

Many brand manufacturers suggest one month but in our personal experience, you can go a fair bit longer. Any fuel stored longer than three months in the engine itself is likely to not be worth your time. 

Once, as a cheeky fix to spark some new life into the fuel that would not start, I added a dash of fresh gas and it helped the chainsaw start, though begrudgingly! 

Check out this way to start a stalled chainsaw or replace a spark plug. If you are interested in safety, check out this Review of Husqvarna wrap around chaps to protect against kickback.
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