The key difference between 2 and 4 Stroke engines is that 2 stroke motors put the oil to lubricate the inside of the motor in the fuel rather than the engine.
Different 2 stroke engines/motors take different amounts (ratios) of oil per litre of fuel and different grades of oil for optimal performance, make sure you read the manual and use the right ratio.
Don’t forget that fuel “goes off” quite quickly 3 – 6 months, be sure to keep an eye on how old your fuel is.
To “mix” fuel for a 2 stroke you need:
- The right 2 stroke oil for your engine.
- The correct fuel:oil ratio for your engine.
- A premix calculator or app.
- A fuel container.
- Straight fuel/petrol.
- A permanent marker.
How to mix 2 stroke fuel (2 cycle gas)
- Lookup how much fuel you want to mix at the right ratio on your premix calculator or app (eg. 10 litres at 50 to 1).
- Add the prescribed amount of oil to the fuel container (eg. 200 mil).
- Add the prescribed amount of fuel (eg. 10 litres).
- Use the permanent marker to label the container.
1. The right stroke oil
You might be able to get away with using any old 2 stroke oil every once and a while, but it’s best to take the manufacturers recommendation of what 2 stroke oil to use.
High performance 2 stroke engines like those found in a motorbike can take fully synthetic 2 stroke oil.
In my opinion spending a few extra dollars on oil is cheap insurance when compared to the hundreds of dollars it’ll cost to repair the engine in the shop.
My motorbike mechanic tells me he can tell from the wear on the pistons if people have been using cheap oil.
Some garden tool brands like Husqvarna have their own brand 2 stroke oils that they recommend.
2. The correct fuel:oil ratio for your engine
The product manual will specify what fuel to oil ratio the engine in your machine is designed to use.
This ratio is usually written like this: 50:1 meaning 50 parts fuel to 1 part oil.
Common ratios include:
- 50:1– Very common
It is important to use the correct ratio, too much oil (too rich) will smoke a lot and choke the motor up with unburnt oil residue.
Too little oil (too lean) will permanently harm the engine and you’ll be up for a costly repair bill.
3. A premix calculator or app
In the old days people use reference charts to work out how much fuel and oil to add to the container, these days it’s easier mix just the right amount you need to keep the fuel fresher by using an calculator or app.
Simply select the ratio and amount of fuel you want to mix and calculator will tell you how much oil is required.
We have created an app for iPhone and Apple watch with and built in calculator and profiles for all your fuel containers, recording the ratio and when you last mixed the fuel.
This app helps you keep track of how old your fuel is, mix just the right amount to keep it fresh and your engines running at their best.
4. A fuel container
Depending on what country you’re in be sure to use a container that conforms to the local safety standards.
Make sure you choose the right sized container for the amount you intend to mix, there’s no point mixing and storing 20 litres of fuel for your trimmer (whipper snipper) which uses only 200 millilitres to fill it. The fuel will be well and truly stale before you use it up.
Too much extra air space in the container can lead to more condensation which is also bad.
In Australia there’s a standard in fuel containers to distinguish between diesel and petrol.
- Yellow is Diesel
- Red or black is Petrol
Don’t be the bozo who turns up with petrol in a yellow container!
5. Straight fuel/petrol
It is not recommended to use high octane fuel for mixing 2 stroke, refer to the manufacturers recommendation for your engine to make sure you are using the correct fuel.
Here in Australia you can normally get 91, 95 and 98 Research Octane Number (RON) fuels at most petrol stations. Opinions vary but it is generally considered that 91 is always the safest bet as it’s the most commonly used so should be the freshest from the petrol station.
6. A permanent marker
Running straight fuel in your 2 stroke will quickly destroy your motor, clearly marking the outside of your container with the fact that it’s 2 stroke, the ratio, and the owner will ensure someone doesn’t make this fatal mistake.
Putting your name on the container is a good idea if you ride motorbikes… you have half a chance of your container returning home if you leave it if the back of someones ute.