Category: Information

Garden 2 Stroke Fuel Container retro BP Zoom

What you need to mix 2 stroke (cycle) fuel

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:

  1. The right 2 stroke oil for your engine.
  2. The correct fuel:oil ratio for your engine.
  3. A premix calculator or app.
  4. A fuel container.
  5. Straight fuel/petrol.
  6. A permanent marker.

How to mix 2 stroke fuel (2 cycle gas)

  1. 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).
  2. Add the prescribed amount of oil to the fuel container (eg. 200 mil).
  3. Add the prescribed amount of fuel (eg. 10 litres).
  4. 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.

Motorex Motorbike two stroke oil
Motorex 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.

Husqvarna garden two stroke oil
Husqvarna 2 stroke oil

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:

  • 25:1
  • 33:1
  • 50:1– Very common
  • 60:1

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.

2 stroke premix calculator iOS app - light mode

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.

Garden 2 Stroke Fuel Container retro BP Zoom

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.

Straight mower fuel container

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.

Motorbike two Smoke Fuel Container

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.

How long does 2 stroke (2 cycle) mixed fuel last?

Opinions on how long a container of pre-mixed 2 stroke fuel will last for varies significantly, some say it is only good for 3 – 4 weeks and others up to 2 – 3 months. In my experience it depends on the motor, but all motors will perform best with a full tank of freshly mixed fuel.

“Fresh is best!”

High Performance Motors

Generally the higher the performance of the motor, then the more noticeable it will be if the fuel is stale.

I had an old suped up outboard race boat that hated stale fuel, it wouldn’t idle and would choke up when you gave it a fist full of throttle when the fuel was going bad. I found it best to run it down quite low and top it up with a fresh jerrycan or two of fuel just before heading out.

Bullet 1650

There were a couple of times where I had to drain the tank where I’d left half a tank or more for over 2 months, there wasn’t enough volume left in the tank to dilute the stale fuel. Your only option is to drain or syphon it out and use it for cleaning in the shed.

Garden Equipment

For your two stroke garden equipment you can get away with leaving it a bit longer, but if you’re having trouble with pull starting, you’re best to throw out the old fuel and start with a fresh batch.

The Facts

BP have an interesting fact sheet on fuel storage, it states that:

“When two stroke fuel is mixed correctly it has the same storage requirements as petrol. Problems arise when excessive two stroke oil is added. Under this condition the oil may separate from the fuel.”

But they also state that fuel store in a fuel tank only lasts about a month:

At the end of five weeks the fuel is 5% heavier and the fuel air mix will contain more fuel. This means your engine will run richer possibly resulting in fouled spark plugs and higher fuel consumption.

As for sealed containers it states:

The storage life of petrol is one year when stored under shelter in a sealed container. Once a seal is broken the fuel has a storage life of six months at 20°C or three months at 30°C.

As stated earlier, “fresh is best” so be sure to mix smaller batches more frequently. Head over to the front page and you’ll find a handy calculator to help you get your mix right.