Mixing of fuel at 40:1 is essential for those who are using 2 stroke engine. If your engine has a proper fuel ratio, it will help to keep your engine lubricated, run smoothly, and avoid damage. If you’re using a 2-stroke engine, using the 40 to 1 fuel mix is one of the most common and reliable options. A proper 40 1 ratio calculator or chart can save you from guesswork and help keep your engine running smoothly.
What is the 40:1 Fuel Mix?
40:1 means that 40 parts of gasoline and 1 part of 2 stoke oil. This ratio provides the right amount of lubrication while keeping the performance balanced.
For Example:
- 1 gallon of gas (128 oz) mixed with 3.2 oz of 2-stroke oil equals a 40:1 fuel-to-oil ratio.
- 5 litres of petrol mixed with 125 ml of oil gives you the same 40:1 mix.
Instead of doing the math yourself, just use this 40 to 1 fuel mix chart, which helps you find the perfect 2-stroke oil mix ratio for any fuel amount in seconds.
40:1 Fuel Mix Formula (Quick Calculation Method)
If you prefer to calculate the fuel mix manually instead of using a chart or calculator, you can use this simple formula:
Oil Required = Fuel Amount ÷ 40
Examples:
- 5 litres of fuel ÷ 40 = 125 ml of 2-stroke oil
- 1 gallon of fuel ÷ 40 = 3.2 ounces of 2-stroke oil
- 10 litres of fuel ÷ 40 = 250 ml of oil
This formula works for any fuel quantity and ensures you always maintain the correct 40:1 ratio.
Manufacturer Recommendation Disclaimer
Always check your engine manufacturer’s manual before mixing fuel.
While 40:1 is a common and reliable ratio, some modern 2-stroke engines require a 50:1 or different fuel-to-oil ratio. Using the wrong mix can affect engine performance and warranty coverage.
40 to 1 Fuel Mix Chart
| Fuel Amount (Litres) | Oil Required (ml) | Fuel Amount (Gallons) | Oil Required (Ounces) |
| 1 L | 25 ml | 1 gal | 3.2 oz |
| 2 L | 50 ml | 2 gal | 6.4 oz |
| 3 L | 75 ml | 3 gal | 9.6 oz |
| 4 L | 100 ml | 4 gal | 12.8 oz |
| 5 L | 125 ml | 5 gal | 16 oz |
| 8 L | 200 ml | 8 gal | 25.6 oz |
| 10 L | 250 ml | 10 gal | 32 oz |
| 20 L | 500 ml | 20 gal | 64 oz |
| 25 L | 625 ml | 25 gal | 80 oz |
| 40 L | 1000 ml (1 L) | 40 gal | 128 oz (1 quart) |
How Long Does a 40:1 Fuel Mix Last?
A properly mixed 40:1 fuel blend should ideally be used within 30 days for best performance.
Storage Tips:
- Use an approved, airtight fuel container
- Store in a cool, dry place away from sunlight
- Adding a fuel stabilizer can extend shelf life up to 90 days
Old or degraded fuel can cause hard starting, poor performance, or engine damage.
How to Mix 40 to One (Gasoline and Oil) Fuel Mixture Safely
- Use a Clean and safe fuel container
- Pour oil first into your approved fuel container.
- Add fresh unleaded gasoline.
- Shake or stir well to make a proper blend.
- Label the container clearly with the ratio used.
Pro tip: If you don’t want to do math every time, use a two-stroke oil mix calculator; it instantly gives you the exact oil measurement.
Common 40:1 Fuel Mixing Mistakes to Avoid
Avoid these common errors to protect your 2-stroke engine:
- Guessing oil measurements instead of using a chart or formula
- Using old or stale gasoline
- Mixing fuel with the wrong type of oil
- Forgetting to shake the container after mixing
- Using a lean mix (too little oil)
Correct mixing ensures better lubrication and longer engine life.
Why This Ratio Matters
- Prevents engine wear and tear
- Reduces carbon buildup
- Delivers consistent power output
- Saves time with accurate mixing
Whether you’re fueling a chainsaw, dirt bike, trimmer, or any 2-stroke machine, the 40 to 1 fuel mix chart ensures your engine gets the perfect balance of fuel and lubrication.
Signs of an Incorrect 40:1 Fuel Mix
If your engine isn’t running properly, your fuel ratio may be the issue.
Warning Signs:
- Excessive smoke → Too much oil
- Engine overheating → Too little oil
- Spark plug fouling → Incorrect mixture
- Poor acceleration or power loss → Improper fuel ratio
Fixing the fuel mix early can prevent serious engine damage.
FAQ’S
1. Is 40:1 the same as 50:1?
No, they’re different. A 40:1 mix has a little more oil than 50:1, which gives better lubrication but can create slightly more smoke.
2. Can I use synthetic 2-stroke oil for a 40:1 fuel mix?
Yes, you can. Just ensure you use high-quality synthetic oil specifically designed for 2-stroke engines.
3. What kind of engines typically use a 40:1 mix?
Many older chainsaws, dirt bikes, outboard motors, and tools that run under heavier loads usually perform well on a 40:1 fuel mix.
4. What happens if I use less oil than the 40:1 ratio?
Running lean (with less oil) can lead to poor lubrication, overheating, or even serious engine damage over time.