FOR FANTASTIC ENGINE POWER WITH LOW MAINTENANCE. The STIHL 4-MIX® engine is a four-stroke engine that does not require any oil circuit components, thanks to refuelling with an oil and gasoline mix. That’s why it’s more compact, more lightweight, and requires less maintenance than conventional four-stroke engines, while at the same time being powerful and offering a comfortable sound pattern. STIHL 4-MIX® engines comply with the European Stage V emissions directive.