There are two calculators here, one for US values and one for metric values. This calculation determines the exact quantity of oil required for a given ratio of gas and oil suggested by the manufacturer of the 2 cycle engine. That calculated number is determined from the amount of gas available for the mixture. That amount is usually an added number, such as 4 gallons, 5 gallons, 10.2 gallons or similar. Enter the number of US gallons of gas added to the tank; the default is 5 gallons. Then, enter the mixture ratio of gas to oil. Most tool, transportation and recreational requirements, such as golf carts, motorcycles, snowmobiles, blowers, chainsaws, tillers, rotary plows, utility tractors, commercial two cycle carts, garden tools, motor scooters, motor skates, some generators and other two cycle engines are in the range of 20:1 to 80:1, gas to oil. Many motorcycles are 32:1, others are 40:1 and still others are 50:1. If you are uncertain, consult your owners manual. Do NOT add oil to the fuel of 4 cycle engines. Enter the ratio value or accept the default.
Click on the Calculate button to find out how many US ounces of specified two cycle oil (or whatever the oil type requirement is for your engine) are required. (Calculations in either calculator will also supply the appropriate converted values for the other.) For 5 gallons of gas, with a 32:1 ratio, the amount of oil required is 20 US ounces (156.25 ml), 4 ounces per gallon of gas (31.25 ml per liter). Experts agree that it is better to err toward the side of too much oil, rather than not enough. Typical break in period ratios are about twice the normal; 32:1 is generally 16:1 during break in. We suggest following the manufacturers guidelines but that is your decision. See our calculator for marine 2 cycle use. Here is some additional oil information that is pretty slick!