2-Stroke Oil Mix — Frequently Asked Questions
[01] How much 2-cycle oil do I mix per gallon?
It depends on the ratio. At 50:1 add 2.56 oz of oil per gallon of gas; at 40:1 add 3.2 oz; at 32:1 add 4 oz; at 25:1 add 5.12 oz. The formula is simply 128 ÷ ratio = ounces of oil per gallon.
[02] What is 50:1 in ounces and millilitres?
A 50:1 mix is 2.56 fluid ounces of oil per US gallon of gas, or 20 ml of oil per litre.
[03] How much oil do I need for 5 gallons at 40:1?
At 40:1 you add 3.2 oz of oil per gallon, so 5 gallons needs 16 ounces of 2-stroke oil (that is one US pint).
[04] What happens if I put too much 2-cycle oil in the mix?
Too much oil makes the engine run rich: it can smoke heavily, foul the spark plug, build up carbon, and lose power. A little extra is far safer than too little, but stick close to the recommended ratio.
[05] Can I run 50:1 instead of 40:1?
Only if your engine and oil are rated for it. A 50:1 mix has less oil than 40:1, so running 50:1 in an engine that calls for 40:1 means less lubrication. Always follow the ratio in your owner's manual or on the oil bottle.
[06] Are 2-cycle and 2-stroke the same thing?
Yes. "2-cycle" and "2-stroke" are two names for the same engine type, where fuel and oil are pre-mixed. This calculator works for both.