2 Stroke Engine Oil - How to Work out the Correct Mix Ratio

This guide helps you calculate the correct petrol to oil ratio for a 2 stroke engine.

Check your owner's manual for the recommended oil and petrol mix ratio for your machine.

The Maths behind the Ratio

This equation allows you to calculate the correct amount of oil to mix with the petrol you have.

We'll use a 50:1 ratio, a common mix for many 2 stroke engines.

Step 1:

First, identify the millilitres.

Divide 1 litre (1000ml) by the 50 in the ratio (see example below).

1000 / 50 = 20

This gives a result of 20.

Step 2:

Next, calculate the amount of oil needed based on the petrol you have and the millilitres identified in step 1.

Multiply the amount of petrol by the millilitres (20ml from step 1). In this example, we have 2 litres of petrol.

2 x 20 = 40

The result is 40, meaning you need 40ml of oil.

This equation works for any amount of petrol. For instance, if you have 5 litres, multiply 5 x 20 to get 100ml.

Recap:

Here's a recap of the equation:

1000 / ratio = ml

Litres of petrol x ml = oil needed

Smart App Alternatives

Above is the manual method for calculating the correct engine oil to petrol ratio.

Apps are available for your smart device that can perform the calculation for you. One useful app is the Castrol 2TRatio app.

It can be downloaded from:

• The Apple App Store
• The Android Google Play Store