# What fuel mix does a 2-stroke garden machine need? 25:1, 40:1 and 50:1 explained

Published 2026-09-30 by the Arbora export team.

**Short answer:** Always use the ratio printed in the machine's manual or on the fuel cap. Many 2-stroke garden machines use 25:1 with standard 2-stroke oil, while 40:1 or 50:1 is used only with high-quality, low-smoke oils approved by the maker. Mix fresh fuel in a clean can and never run straight petrol in a 2-stroke engine.

## What does 25:1 actually mean?

It means 25 parts petrol to 1 part 2-stroke oil by volume. For 1 litre of petrol at 25:1 you add 40 ml of oil; at 40:1 you add 25 ml; at 50:1 you add 20 ml.

| Petrol | 25:1 | 40:1 | 50:1 |
|---|---|---|---|
| 1 L | 40 ml | 25 ml | 20 ml |
| 5 L | 200 ml | 125 ml | 100 ml |

## Why do ratios differ between machines?

The ratio depends on the engine's tolerances and the oil the maker tested. Several of our chainsaws, for example, list 25:1 in their specifications. Using more oil than needed causes smoke and carbon; using less risks a seized piston.

## How should operators mix fuel?

1. Use fresh petrol of the octane the manual specifies.
2. Pour half the petrol into a clean, marked can.
3. Add the full measure of 2-stroke oil.
4. Close and shake, then add the remaining petrol and shake again.
5. Use the mix within about 30 days and shake before refuelling.

## What are the most common mistakes?

- Running straight petrol, which ruins the piston and cylinder in minutes.
- Using 4-stroke engine oil instead of 2-stroke oil.
- Storing mixed fuel for months, which leads to gummed carburettors.

## What should distributors do?

Print the ratio clearly on the fuel tank, include a marked mixing bottle with each machine and translate the fuel instructions into your customers' language. We can add your ratio label and mixing bottle at the factory.