Two stroke engines require an oil and fuel mixture for the engine to run properly. The reason for this is that most two stroke engines don't have separate lubrication systems, so the fuel has to also provide lubrication to the moving parts of the engine.
One of the reasons that two stroke engines produce more smoke than four stroke engines is because of this—the engine is burning oil as well as fuel. Most modern two stroke engines suggest a 50:1 gasoline-to-oil ratio to power the engine. Some chainsaw operators feel more comfortable using extra oil in their mixtures because it provides additional lubrication, but this could also cause heavier smoke than normal. In any case, you should check your owner’s manual for the recommended ratio, or if you have an old chainsaw, mix a higher ratio such as 40:1 or 30:1 just to be on the safe side.
Here is the process:
- Get two stroke engine oil, such as Lucas Two Cycle Oil, and unleaded, 89 octane (or higher) gasoline. It's important to use two-stroke engine oil only because it is specially formulated for two-stroke engines to prevent build up in the engine.
- Measure out your ratio according to the recommended amount. This calculator is a handy way to figure out the exact measurement of oil in ounces you need for the corresponding amount of gas in gallons. The corresponding measurements for 50:1 are 2.6 ounces of oil for every gallon of gas.
- To mix the solution effectively, you can add half the amount of gas and the full amount of oil to a gas container and shake the container. Add the rest of the gas and shake again. Don't try to mix the oil and gas in the fuel tank of your chainsaw, as it will be difficult to get the measurements right. You will also want to mix more than will fit in your chainsaw's gas tank so you have some extra on hand for refueling later.
- As an optional step, you can add a fuel enzyme treatment that will stabilize your fuel and ensure that your gasoline stays good for up to 2 years. Many gasolines now contain ethanol, and enzyme treatment will help to stabilize your fuel and prevent problems that arise from ethanol containing fuel.
- Now it’s time to fill up your fuel tank. There are a few things to remember when fueling your chainsaw:
- Always wipe up any excess spillage on your chainsaw.
- Start your machine at least 10 feet away from where you refueled.
- Always start your chainsaw in a very well-ventilated area.
If you have various cans of gasoline, it doesn't hurt to label the can you just mixed with the ratio to help you remember what mixture you made in that can. You should also always shake the container before refueling your chainsaw because the oil and gas will become separated after the mixture settles.