- Much of the gasoline sold throughout the United States contains ethanol. The maximum ethanol content allowed by law for use in outdoor power equipment is limited to 10% (E10). Make sure the gasoline you purchase for your outdoor power equipment contains no more than 10% ethanol. If the filling station pump is not labeled with the ethanol content, ask the station attendant what percentage of ethanol is in the gasoline.
- Ethanol can dissolve varnish and gum deposits that have previously formed inside fuel storage cans or the equipment’s engine. When these deposits become dislodged, they can mix with the fuel and plug small openings and filters within the fuel system.
- Ethanol attracts and mixes with moisture in the air, causing corrosion to metal components in the fuel system. If enough water is absorbed, the ethanol and water will settle out of the gasoline blend and settle to the bottom of the equipment’s tank. The layer of gasoline left floating on top has a lower octane level than the original ethanol gasoline blend, which can result in unstable engine operation, power loss and major engine failures.
- Since the fuel is often drawn from the bottom of the fuel tank, the engine is drawing in a mixture of ethanol and water with no gasoline and no lubricating oil. This ethanol/water mix is thicker than gasoline and cannot easily pass through the fuel system. This can result in hard starting, unsafe high idle speeds, stalling, and can ultimately lead to engine damage or fuel system failure.
Guidelines for using E10 gasoline in STIHL power equipment:
If the proper precautions are taken, gasoline containing a 10% quantity of ethanol can safely be used in your STIHL products.
- Use a minimum of 89 octane gasoline and always use fresh fuel. Only buy enough gasoline that you can easily use up within a two-month period or use a specially formulated fuel mixture like STIHL MotoMix® Premixed Fuel. STIHL MotoMix® is a high-grade, high-octane, ethanol-free premixed fuel containing STIHL HP Ultra synthetic oil. It is a pure and stable fuel mixture that can be stored for up to two years in the original container and is ideal for machines that are used infrequently.
- For air-cooled, two-cycle engines, use a quality mix oil that meets the engine manufacturer’s recommendations. All STIHL oils are designed to readily mix with gasoline containing 10% ethanol.
- Properly store your equipment. If your equipment is not going to be used for a couple of months, the remaining gasoline in the machine should be drained from the tank and disposed of properly. To ensure that any remaining ethanol is removed from your equipment, STIHL recommends adding a small amount of STIHL MotoMix® Premixed Fuel to the tank and running the engine for a few minutes to circulate the fuel through the carburetor.
- Equipment should be serviced regularly by your STIHL Dealer. Items such as fuel filters, fuel lines, carburetor diaphragms and spark plugs should be checked and replaced if necessary as part of a normal engine tune-up.