| Ratio | Oil per US Gallon |
|---|
Mixing Two-Stroke Fuel
Two-stroke engines, the kind in chainsaws, string trimmers, leaf blowers, outboard motors, and many dirt bikes, do not have a separate oil sump. They lubricate by burning oil mixed into the gasoline. Get the ratio right and the engine runs clean and lasts; get it wrong and you risk seizing it or fouling the plug.
Reading the Ratio
A ratio like 50:1 means fifty parts gasoline to one part oil. A bigger first number means less oil. Modern equipment often calls for 50:1, older gear may want 32:1 or even 16:1, and some specialty oils run 100:1. The number printed on your equipment or in the manual always wins.
Practical Mixing Tips
Measure the oil precisely, add it to the empty can first, then pour in the gasoline so it blends as it fills. Mix only what you will use in about a month, since ethanol fuel goes stale and separates. A fuel stabilizer helps if it will sit longer.
Frequently Asked Questions
What if I use too much oil?
A little extra oil smokes and can foul the spark plug but rarely harms the engine. Too little oil is the dangerous direction and can cause a seizure.
Can I run straight gas in a two-stroke?
No. Without oil in the fuel the engine has no lubrication and will fail quickly. Never run a two-stroke on pure gasoline.
Does the gas octane matter?
Use the octane your equipment specifies, and prefer ethanol-free fuel for small engines when available, as it stores better and is easier on seals.