Stihl HP Ultra is a new, all-synthetic high-performance engine oil developed in-house. It is ideal for air-cooled two-stroke and 4-MIX engines with a mix lubrication system, with or without a catalytic converter. Stihl HP Ultra combines excellent lubrication with a very low tendency to carbonizing. The result is excellent lubrication and excellent protection for your high-performance engine, especially in continuous operation under full load.