Two-stroke engines depend on a mixture of gasoline and engine oil for lubrication and cooling. Unlike four-stroke engines, which have separate oil reservoirs, two-stroke engines require pre-mixed fuel to maintain the protection of very important engine components during operation.
A 100:1 fuel-to-oil Ratio Means
100 Parts Gasoline to 1 Part Two Stroke Engine Oil
This ratio is commonly used in modern two-stroke engines to achieve cleaner with minimal smoke. Manufacturers who recommend a 100:1 ratio typically use higher-quality materials and more smooth-running internal lubrication in their engine designs.
Why Use a 100:1 Ratio?
- Benefits of a 100:1 ratio include
- Reduced emissions and odor
- Reduced carbon build-up on spark plugs and exhaust pipes
- Cleaner engine performance with modern synthetic oils
- Economical – less oil is needed per tank.
However, always consult your tool manual to confirm the correct mixing ratio. Using too little oil in engines not designed for a 100:1 fuel-oil mixture can cause wear and tear or damage especially in older, high-speed, or commercial equipment.
How to Measure a 100:1 Fuel-Oil Mix
- The equation is simple:
- Fuel Volume ÷ 100 = Oil Volume
Examples
- 2 liters of fuel → 20 ml of oil
- 1 gallon of fuel → 1.28 fl oz of oil
For easy measurements, please use the pre-mixed oil volume chart below.
100:1 Premix Fuel Mix Chart
Metric (Litres → mL of Oil)
| Fuel (L) | Oil (mL) |
| 0.5 | 5 |
| 1 | 10 |
| 1.5 | 15 |
| 2 | 20 |
| 2.5 | 25 |
| 3 | 30 |
| 4 | 40 |
| 5 | 50 |
| 7.5 | 75 |
| 10 | 100 |
| 15 | 150 |
| 20 | 200 |
| 25 | 250 |
US (Gallons → Fluid Ounces of Oil)
| Fuel (gal) | Oil (fl oz) |
| 0.5 | 0.64 |
| 1 | 1.28 |
| 1.5 | 1.92 |
| 2 | 2.56 |
| 2.5 | 3.2 |
| 3 | 3.84 |
| 4 | 5.12 |
| 5 | 6.4 |
| 7.5 | 9.6 |
| 10 | 12.8 |
| 15 | 19.2 |
| 20 | 25.6 |
| 25 | 32 |
Engines That Use a 100:1 Fuel/Oil Ratio
Common equipment includes
- Light-duty lawn mowers and brushcutters
- High-speed hedge trimmers and chainsaws
- Modern hand blowers
- Some small boat engines
Since fuel mixture ratios vary between engines, always follow the manufacturer’s instructions printed on your equipment or fuel tank cap.
Safety and Quality Tips
- Use a high-quality synthetic two-stroke engine oil.
- Shake the container well before use.
- Mix only enough for 30 days of use.
- Store fuel in an airtight, certified container.
- Never use pure gasoline to run a two-stroke engine.
Use 2 Stroke Oil Mix Calculator for more accurate 20:1, 24:1, and 32:1 Ratios