Aspen 2 fuel is a ready-mixed (2%) alkylate petrol for all 2-stroke small capacity engines with a recommended mix of 2% or 1:50. It is mixed with a synthetic high quality high performance 2-stroke oil for maximum protection and low smoke. This 2-stroke ready-mixed alkylate petrol contains no sulphur, benzene or aromatics. It is therefore much better from a health aspect to use than regular petrol. In fact normal petrol contains so much benzene and aromatics (read solvents) that it is a real health risk to use in 2-stroke engines. Aspen 2T is also chemically inert so you can comfortably leave the fuel in the machine and it will not gum-up. It will also store for years whereas normal petrol start to go off after 30 days.