How to prevent petrol from being flammable?
Nearly every solvent is flammable, some exceptions are halogenated hydrocarbons. But plain hydrocarbons are pretty much all flammable, though some are more dangerous than others like e.g. diethyl ether.

Chloroform is non-flammable, but due to the toxicity I would not recommend to use it. There are some other non-flammable solvents for cleaning mentioned in this presentation from NASA on the search for non-flammable solvents. But it seems that many candidates are being phased out because they are a hazard to the ozone layer.