Two Stroke Fuel Mix Calculator
To achieve the desired ratio, add:
Understanding Two-Stroke Fuel Ratios
Two-stroke engines, commonly found in chainsaws, leaf blowers, dirt bikes, and outboard motors, do not have a dedicated oil reservoir like a car engine. Instead, they rely on oil mixed directly into the gasoline to lubricate the cylinder, piston, and crankshaft.
Getting the ratio right is critical. A mix that is "too lean" (not enough oil) can cause the engine to overheat and seize. A mix that is "too rich" (too much oil) leads to spark plug fouling, excessive blue smoke, and carbon buildup inside the engine.
Common Mixing Ratios
Always check your owner's manual for the specific requirements of your equipment. Here are the most common industry standards:
| Ratio | Application | Oil per 1 Gallon | Oil per 5 Liters |
|---|---|---|---|
| 25:1 | Older vintage engines | 5.12 oz | 200 ml |
| 32:1 | High-performance dirt bikes | 4.0 oz | 156 ml |
| 40:1 | Standard lawn equipment (Husqvarna/Echo) | 3.2 oz | 125 ml |
| 50:1 | Modern hand-held tools (Stihl) | 2.6 oz | 100 ml |
Real-World Examples
Example 1: You have a 5-gallon gas can and a modern Stihl chainsaw that requires a 50:1 ratio. Using the calculator, you'll see you need 12.8 fl oz of 2-cycle oil.
Example 2: You are in Europe with a 10-liter canister and an older outboard motor requiring a 25:1 ratio. You will need exactly 400 ml of oil to protect that engine properly.
Tips for Perfect Mixing
- Always use 2-cycle oil: Never use standard automotive motor oil (4-stroke oil) as it won't burn correctly.
- Fresh Fuel: Ethanol-blended fuels can attract moisture and degrade the oil mix over time. Use fresh gas, preferably ethanol-free, for best results.
- Mix in the Can: Never pour gas and oil separately into the machine's fuel tank. Mix them in a dedicated fuel canister first to ensure an even blend.
- Shake it up: Give the gas can a good shake before every use to prevent the oil from settling at the bottom.