Gas Oil Mix Chart (How to Mix Your Own)

What is the purpose of mixing gas with oil for small engines? How do you do it? How can you tell which mix ratio to use? Does my power equipment need it? This is an important topic to prevent premature small engine damage, here is what you need to know.

Small engines generate a lot of heat, most of which dissipates into the air through cooling fins on the engine block. 2-stroke engines need additional cooling help because they don’t have an internal oiling system to lubricate and keep the engine cool.

Burning gasses create heat, but so does friction, and oil reduces friction inside the cylinder during combustion. Adding a small amount of oil to the fuel in a 2-stroke engine is important because it helps the engine run cooler.

Gas can and oil container for gas/oil Mixing

Most 2 stroke small engines, such as those found on mowers, blowers and trimmers, require a gas oil mixture ratio of 40 to 1. Some small engines, like those on Stihl chainsaws, require a 50 to 1 gas oil mixture, so check manufacturer specs before mixing. This gas oil mix chart shows how much oil to add to the gas.

Too much or too little oil will cause performance issues, so getting the right fuel to oil mixture is extremely important.

Gas Oil Mix Chart For 2-Cycle Engines

Mix Ratio Gas Volume 2-Cycle Oil
Imperial Fluid Ounces
32 To 1 1 gal. 4 oz.
40 To 1 1 gal. 3.2 oz.
50 To 1 1 gal. 2.6 oz.
Metric Fluid Milliliters
32 To 1 1 liter 31.25 ml
40 To 1 1 liter 25 ml
50 To 1 1 liter 20 ml

Do 4-Cycle Small Engines need mixed gas oil?

4-cycle small engines do not need oil added to the gas, they have an oil reservoir to hold the oil. This is because they have a built-in oiling system to provide lubrication and cooling.

Do not mix oil into the gas for 4-cycle engines unless the manufacturer recommends it.

Is My Small Engine 2 Stroke or 4?

The easiest way to tell if a small engine is a 2 stroke or 4 stroke is by looking for an oil reservoir on the engine. If present, it will have a filler tube and possibly other markings telling you that’s where the oil goes.

All small engines require oil, either in the oil reservoir or mixed with gas, so remember that oil reservoirs are on 4-stroke engines and no oil reservoir means 2-stroke engine. Only add oil to the gas of 2-stroke engines.

Pre-Mixed 2 cycle Gas

Pre-mixed 2 cycle gas is available at most hardware stores. A gas stabilizing agent is typically added to ready mixed gas to give it a longer shelf life.

The downside to buying ready mixed gas is that it tends to be more expensive than mixing gas and oil yourself.

Additionally, mixing gas and oil yourself allows you to control the octane and ethanol levels of the gas. Mixing it yourself is often cheaper than buying pre-mixed gas.

Gas Oil Mixing Suggestions

  • Use a clean container to store mixed gas
  • Write the mix ratio on the side of the container
  • Mix and store gas outdoors in a well ventilated area
  • Use 2 cycle oil, regular motor oils contain additives
  • Mix only what you will need for one season

Common gas oil mix related questions

  • Which ratio has more oil? (40 or 50 to 1)
  • A 40 to 1 gas oil mixture contains more oil than a 50 to 1 mixture when the total volume is the same.

  • Is 2-stroke and 2-cycle the same thing?
  • Yes, both terms refer to the number of piston strokes per complete combustion cycle, they mean the same thing.

  • How long can 2 stroke gas be kept?
  • 2-stroke oil has a shelf life of 5 years if unopened and 2 years once unsealed. After mixing 2-stroke oil with gas, the gas can be safely stored for 2-3 months before it begins to separate and degrade.