2-Stroke fuel mix: exact oil ratio by brand (2026)
M
Max
|3 minJanuary 9, 2026
Why the right mix is critical
In a 2-stroke engine, the oil mixed with petrol is the only lubricant. There's no separate oil sump. If the mix is too lean on oil, the piston and cylinder aren't lubricated enough, leading to seizure (destroyed engine). If the mix is too rich, the engine fouls up, loses power, and the spark plug drowns.
The right ratio is therefore a vital balance between lubrication and clean combustion.
The ratios: conversion table
Ratio
Oil per liter of petrol
Typical use
50:1
20 mL
Modern standard (Stihl, Husqvarna, Echo, most current manufacturers)
40:1
25 mL
Some Japanese models (Tanaka, older Shindaiwa)
32:1
31 mL
Older models (pre-2000s)
25:1
40 mL
Very old engines, some marine models
When in doubt, use 50:1 with synthetic oil. It's the most widespread standard today. Always check your tool's manual — the ratio is indicated on the tool itself or in the instructions.
For common volumes
At 50:1 (most common):
1 liter of petrol → 20 mL of oil
5 liters of petrol → 100 mL of oil
10 liters of petrol → 200 mL of oil
At 40:1:
1 liter of petrol → 25 mL of oil
5 liters of petrol → 125 mL of oil
At 25:1:
1 liter of petrol → 40 mL of oil
5 liters of petrol → 200 mL of oil
Synthetic vs mineral oil
Synthetic 2-stroke oil (recommended):
Better lubrication at high temperatures
Cleaner combustion (fewer deposits)
Allows leaner ratios (50:1)
Price: 8-15 euros per liter
Mineral 2-stroke oil:
Cheaper (4-8 euros per liter)
Often requires richer ratios (40:1 or 32:1)
Produces more smoke and residue
Acceptable for occasional use
Never use: 4-stroke engine oil (10W-40, 15W-40...), used drain oil, or cooking oil. These oils don't mix properly with petrol and will destroy the engine.
The method for a perfect mix
Use a clean, graduated container — never the tool's tank directly
Pour the oil first into the container
Add half the petrol, close, shake vigorously
Add the remaining petrol, close, shake again
Let it rest for 1 minute before pouring into the tank
The order matters: oil first allows better mixing. If you pour oil onto petrol, it tends to float without mixing evenly.
Storage: 30 days maximum
This is the most often overlooked point. The petrol/oil mix has a limited shelf life:
Fresh (< 30 days): normal use
30-60 days: mix degrades, difficult starting possible
> 60 days: discard. The petrol has oxidized, light components have evaporated, deposits form in the carburetor
Storage tips:
Write the preparation date on the container
Store in a metal or opaque plastic container, out of sunlight
Prepare small quantities (1-2 liters) rather than a large container
At season's end, drain the tank and run the engine until it stalls
Petrol: regular or premium?
Regular unleaded (E5): the standard choice. 5% ethanol maximum, compatible with all 2-stroke engines.
Premium unleaded (E5): slightly better (higher octane = smoother combustion). Recommended for high-performance pro tools.
E10: contains 10% ethanol. Ethanol attacks seals, carburetor diaphragms, and attracts water. Avoid when possible for small 2-stroke engines. If you have no choice, use the mix within 15 days.
Alkylate fuel (Aspen, Motomix...): ethanol-free, benzene-free fuel with long shelf life (2+ years). Ideal for long-term storage, but 3-4 times more expensive. The best choice if you use your tool occasionally.
Try L'Atelier free for 10 days — no credit card required. Find the mix ratio and recommended oil type for your model.
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