Not all gasoline is the same. Knowing a few facts about your fuel can keep the engines in your STIHL equipment running strong.

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 90 octane gasoline and always use fresh fuel. Only buy enough gasoline that you can easily use up within a two-month period.
  • 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.

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.

Fuel mixture

Your petrol-powered engine requires a mixture of petrol and engine oil. The quality of the petrol and oil is extremely important to the running and life of the engine.

Unsuitable fuels or mix ratios that do not comply with the specification can seriously damage the engine (piston seizing, excessive wear.)

Always use high-quality petrol with a minimum octane number of 90 RON (we recommend using unleaded to protect your health and the environment).

We recommend the following mix ratios:

We recommend the following mix ratios:

for STIHL 1 : 50 two-stroke engine oil:
1 : 50 => 1 part oil + 50 parts petrol

For other high-quality two-stroke engine oil with the TC classification:
1 : 25 => 1 part oil + 25 parts petrol

> 1 part oil + 25 parts petrol

Mixing ratios

For a mixing ratio of 1 : 50 you need 5 litres of petrol and 0.10 litres (100cm³) of STIHL two-stroke oil.

Petrol quantitySTIHL two-stroke oil 1:50Other brand name two-stroke engine oils 1:25
LitresLitrescm³Litrescm³
10.02(20)0.04(40)
50.10(100)0.20(200)
100.20(200)0.40(400)
150.30(300)0.60(600)
200.40(400)0.80(800)
250.50(500)1.00(1000)

What you need to know about Ethanol:

  • 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.