Fuel Additives from dcarbon's blog

Fuel additives and concentrated solvents operate similarly.  Fuel additives are in lower concentration and added to several tanks of gas.  Concentrated solvents flush the injectors and combustion chamber at a faster rate and is a service that can be conducted at the service station.  Both, however, have inherent risks.  Some combustion chambers may be lined with a teflon-like coating that can be damaged - Pass Smoke Test.