2-Stroke Engine Oil Mix Ratio

Two-stroke engines are commonly found in various handheld equipment, such as string trimmers, chain saws, polesaws, brushcutters, and leaf blowers. Unlike four-stroke engines, these engines require a mixture of fuel and oil to be added to the fuel tank. This mixture serves the purpose of both engine combustion and lubrication. Operating a 2-stroke engine solely on gasoline can lead to engine failure.

Determining the Correct Mix Ratio

The appropriate mix ratio for a 2-stroke engine depends on the equipment’s manufacturing year. This information can usually be found near the model number.

Equipment Manufactured Before 2003

• Use a 32:1 gasoline to oil ratio.
• Combine one gallon of gasoline with 4 ounces of 2-cycle engine oil.
• In the state of California, use a 2-cycle oil mix ratio of 40:1.

Equipment Manufactured After 2002

• Use a 40:1 2-cycle oil mix ratio.
• Combine one gallon of gasoline with 3.2 ounces of 2-cycle engine oil.

Unsure of the Equipment’s Age?

• Opt for the 40:1 mixture. All handheld 2-cycle units can operate on a 40:1 2-cycle oil mix ratio.

Calculating the Oil Quantity

To determine the exact amount of oil needed for a specific quantity of gasoline, follow this simple formula:

Oil Volume = Gasoline Volume (in liters) x 25

For instance, if you have 3 liters of gasoline, the calculation would be as follows:

Oil Volume = 3 liters x 25 = 75 milliliters

Therefore, you would need 75 milliliters of 2-cycle oil for 3 liters of gasoline.

Mixing the Fuel and Oil

1. Pour the 2-cycle oil into an empty gasoline can before adding a gallon of fresh gasoline.
2. No additional agitation is necessary.
3. If the mixture may be stored for more than 30 days, add a fuel stabilizer to the gasoline before mixing to extend its shelf life.
4. Label the gas can containing the 2-cycle oil mixture to prevent accidental use in other equipment.

Note: Never use gasoline with an ethanol content higher than 10%. Ethanol attracts moisture when exposed to air. After absorbing less than an ounce of water, the 2-cycle gasoline and oil mixture will start to separate, potentially damaging your engine’s carburetor if used.

Conclusion

By following the appropriate mix ratio and mixing instructions, you can ensure the proper functioning and longevity of your 2-stroke engine. Always refer to the equipment manufacturer’s recommendations for specific mix ratios and handling instructions.

Sources:

• https://www.mtdparts.com/en_US/knowledge-2-cycle-oil-ratio-maintenance.html
• https://2strokemix.com/40-to-1-fuel-mix-chart/
• https://www.goldeagle.com/tips-tools/2-cycle-oil-mix-calculator-chart/

FAQs

What is the mix ratio for 40 to 1?

The mix ratio for 40 to 1 means that for every gallon of gasoline, you need to add 3.2 ounces of two-cycle engine oil.

How do I calculate the amount of oil needed for a specific quantity of gasoline?

To calculate the amount of oil needed, multiply the liter amount of gasoline by 25 to determine the milliliters of oil required. For example, for 3 liters of gasoline, you would need 3 x 25 = 75 milliliters of oil.

What is the reference chart for the 40 to 1 mix ratio?

The reference chart for the 40 to 1 mix ratio is as follows:

• 1 liter of gasoline requires 25 milliliters of oil
• 2 liters of gasoline require 50 milliliters of oil
• 3 liters of gasoline require 75 milliliters of oil
• 4 liters of gasoline require 100 milliliters of oil
• 5 liters of gasoline require 125 milliliters of oil

Do all 2-stroke engines use the same mix ratio?

No, different equipment may require different mix ratios. For example, most handheld equipment manufactured before 2003 may require a 32:1 ratio, while most handheld equipment made after 2002 may use a 40:1 or 50:1 ratio. Most outboard motors typically require a 50:1 ratio.

How do I mix the fuel and oil?

To mix the fuel and oil, pour the 2-cycle oil into an empty gasoline can before adding a gallon of fresh gasoline. No additional agitation is necessary. If the mixture may be stored for more than 30 days, add a fuel stabilizer to the gasoline before mixing to extend its shelf life.

How do I know if my 2-stroke engine is getting enough oil?

Signs that your 2-stroke engine is getting enough oil include:

• The engine runs smoothly without excessive noise or vibration.
• The spark plug is not fouled with excessive carbon deposits.
• The exhaust smoke is blue or white, not black.

What happens if I use too much oil in the mix?

Using too much oil in the mix can cause:

• Fouled spark plugs
• Increased carbon deposits
• Reduced engine performance
• Engine damage

What happens if I use too little oil in the mix?

Using too little oil in the mix can cause:

• Increased engine wear
• Scoring of the cylinder walls
• Piston seizure
• Engine damage