Mixing Oil and Fuel for 2-Cycle Engines

Are you wondering how to pre-mix 2-stroke oil? Need to know the oil to fuel ratio your power equipment needs?

A 2-cycle oil mix chart, an oil / fuel mix calculator, and mixing guide can help answer those questions and more. Let's get mixing, the right way.


What is a 2-Cycle Engine

A 2-cycle engine, also known as a two-stroke engine, is an internal combustion engine that completes a power cycle in two strokes of the piston (one up and one down).

Unlike four-stroke engines, which have separate intake and exhaust strokes, a two-stroke engine combines these functions in a single compression and combustion cycle.

Two-stroke engines, favored for their simplicity and high power-to-weight ratio, commonly power lightweight machines such as chainsaws, handheld trimmers, lawn mowers and the outboard motors of small boats.

2-Cycle Engines Need Mixed Fuel

Two-stroke engines require an oil-fuel mixture for lubrication, cooling, and sealing.

Unlike four-stroke engines, they lack a separate oil system, so oil is mixed directly with the fuel to ensure essential engine functions and prevent wear.

Maintaining the correct oil-to-fuel ratio is crucial for optimal performance and longevity.


Common Mix Ratios

Common mix ratios for two-stroke engines include 50 to 1, 40 to 1, and 32 to 1.

These ratios represent the proportion of fuel to oil in the mixture, with the 1 representing the amount oil and the larger number representing fuel.

Follow the manufacturer's recommendations for the specific equipment to ensure proper lubrication and performance.

Use the following chart to get the mix amounts right.

Oil Mix Chart

Mix RatioGas Volume2-Cycle Oil
Imperial Fluid Ounces (US)
32 To 11 gal.4 oz.
40 To 11 gal.3.2 oz.
50 To 11 gal.2.6 oz.
Metric Fluid Milliliters (Canada)
32 To 11 liter31.25 ml
40 To 11 liter25 ml
50 To 11 liter20 ml

Oil Mix Calculator

2-cycle Oil Mix Calculator


How to Mix 2 Cycle Oil

2-Cycle Oil Mix

To mix 2-cycle oil:

  1. Check Ratio: Confirm the manufacturer's recommended oil-to-fuel ratio for your specific 2-stroke engine.
  2. Use Measuring Tools: Use a dedicated measuring cup or ratio-specific container to ensure precise measurements.
  3. Pour Fuel First: Pour the required amount of gasoline into a clean, approved container.
  4. Add Oil: Add the appropriate amount of 2-cycle oil to the container following the recommended ratio.
  5. Secure Lid: Close the container tightly and shake it well to achieve a thorough and consistent mixture.
  6. Fuel Up: Pour the mixed fuel into your 2-stroke engine's fuel tank and follow the manufacturer's instructions for starting and running.

2-Cycle Engine or 4?

The easiest way to tell if a small engine is a 2-cycle or 4-cycle engine is by looking for an oil reservoir or oil filler tube on the engine.

All small engines require oil, either in the oil reservoir or mixed with gas, so remember that oil reservoirs and filler tubes, with caps possibly marked "oil", are on 4-stroke engines.

Only add oil to the fuel of 2-stroke engines.


Using Synthetic Oil

Yes, you can use synthetic oil when mixing 2-stroke fuel, but always check with the manufacturer for specific instructions. Here are the benefits.

  1. Reduced Friction: Synthetic oils provide superior lubrication, reducing friction between moving parts and minimizing wear on crucial engine components.
  2. Cleaner Combustion: Synthetic oils often burn cleaner than conventional oils, resulting in reduced carbon deposits and minimizing exhaust emissions.
  3. Enhanced Temperature Stability: Synthetic oils can withstand higher operating temperatures, providing better protection against thermal breakdown and maintaining viscosity in extreme conditions.
  4. Reduced Deposits: Synthetic oils are less prone to forming deposits on engine surfaces, leading to cleaner combustion chambers and improved overall engine cleanliness.
  5. Extended Engine Life: The superior lubricating properties of synthetic oils contribute to reduced engine wear, potentially extending the lifespan of 2-stroke engines.
  6. Better Cold-Start Performance: Synthetic oils often have better cold-flow properties, ensuring smoother starts in colder temperatures, which is beneficial for 2-stroke engines in various applications.
  7. Improved Fuel Efficiency: The reduced internal friction and cleaner combustion associated with synthetic oils may contribute to improved fuel efficiency in 2-stroke engines.

Mixture Safety

When handling, mixing, and storing oil and fuel, make sure to do so in well-ventilated areas, away from heat sources and open flames, prioritizing safety.

Be aware of the flammability of the mixture, and follow proper disposal guidelines for used oil.

Regularly check your equipment for leaks and use approved containers to further enhance safety, making conscientious fuel and oil mixture practices a fundamental aspect of your 2-stroke engine maintenance.

Mixed Fuel Shelf Life

The shelf life of mixed fuel (gasoline and oil mixture) for 2-cycle engines depends on various factors, including the type of oil used, storage conditions, and the presence of stabilizers. Here are some general guidelines:

  1. Without Stabilizers:
    • If you mix fuel with 2-cycle oil and store it without any stabilizers, it's generally recommended to use the fuel within 30 days. After this period, the fuel may start to degrade, and the effectiveness of the oil in the mixture may diminish.
  2. With Fuel Stabilizers:
    • If you use a fuel stabilizer, it can extend the shelf life of the mixed fuel. Many stabilizers are designed to prevent the breakdown of gasoline over time. Follow the instructions on the stabilizer product for specific guidance on storage duration.
  3. Type of Oil:
    • The type of 2-cycle oil used can also impact the stability of the mixture. High-quality synthetic oils often provide better stability compared to conventional oils.
  4. Storage Conditions:
    • Store the mixed fuel in a cool, dry place away from direct sunlight. Exposure to extreme temperatures and sunlight can accelerate the degradation of the fuel.
  5. Engine Performance:
    • Even if the fuel is within the recommended storage period, it's a good practice to periodically check the fuel quality. If the fuel has a strong odor, has separated, or shows signs of contamination, it may be advisable to replace it.

Fuel Mixing FAQs

Which ratio has more oil, 40 or 50 to 1?

A 40 to 1 fuel mixture contains more oil than a 50 to 1 fuel mixture.

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.

Share Your Experiences

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