You may have heard of E15, the newly approved higher-ethanol fuel.  The concept is simple: it is a blend of gasoline and up to 15% ethanol.  Ethanol is a fuel that is most commonly made from corn.  Most gasoline sold in the US today has an ethanol content of about 10%.

E15 can be very corrosive to rubber and certain metals.  If left in a tank for too long, the ethanol forms a thick brown substance that can clog engine components.  Because of this, it is only safe to use in certain engines.  According to the Environmental Protection Agency, it is safe for use in flexible-fuel vehicles (FFVs) and cars, light-duty trucks, and medium-duty SUVs that are mile year 2001 or newer.  Vehicles in which it is not safe to use E15 are motorcycles, all heavy-duty engines (buses, delivery trucks, et cetera), all off-road vehicles (boats, snowmobiles, et cetera), and all vehicles that are mile year 2000 or older.

So what about power equipment?

The EPA has not approved E15 for use in smaller engines such as lawn mowers and other power equipment.  Because of its corrosive nature and the fact that it makes two-stroke engines run hotter than normal — accelerating engine wear — it is not only unsafe, but would significantly reduce the life of your engine.  So to keep your equipment running like new season after season, avoid E15.