All small equipment manufacturers specify the gasoline-to-oil ratio a two-cycle engine requires in the operator's manual for individual products. Many manufacturers also stamp the required ratio directly onto the machine's fuel tank or gas cap. If the manual is unavailable, contact the manufacturer for a replacement.
The three most common gasoline-to-oil ratios for two-cycle engines are 32:1, 40:1 and 50:1. The larger number always refers to the amount of gasoline the mixture requires. For instance, an engine that requires a 32:1 ratio requires mixing one gallon of gasoline with four fluid ounces of two-cycle oil, while a 50:1 engine requires 2.6 fluid ounces of oil for every gallon of gasoline.
Always mix the fuel and oil in a clean gas can large enough for the entire mixture. Pour the measured amount of oil into the gas can first, and add the gasoline afterward. Adding the gasoline last ensures the fuel and oil mix sufficiently. Never mix the oil and gas in the engine's own gas tank. The two liquids almost never completely mix in this case, potentially causing major engine damage.
Many small-engine equipment manufacturers produce their own brands of two-cycle engine oil. Unless explicitly stated in the owner's manual, using these products is not necessary. Generic brands of two-cycle oil are more affordable and just as safe and effective as the manufacturer's products.