Answer: The fuel-oil mixture ratio for all Weed Eater products is 40:1. You can obtain this ratio by mixing 3.2 oz. of oil with one gallon of regular gas. If you have other brands of equipment that require different fuel/oil ratios and you don't want to mix separate fuel cans, you should use the lowest numerical ratio. For example, if you have products requiring 40:1, 50:1, and 32:1 ratios you should use the 32:1 ratio for all products. This may cause slight smoke increase in the exhaust in the 40:1 and 50:1 products due to more oil in the fuel, but it won't damage either of the engines. this was taken from the FAQ's at www.weedeater.com
aa, May 2005