Five fuels have been tested for 200 hours each in five separate but physically identical engines. The five fuels are, two shale oil-derived gasolines, two coal-derived gasolines, and one baseline unleaded gasoline. The results reported in this paper describe the tendency of the fuels to undergo postignition-induced-knock, and the indicators used for predicting the severity of this knock. The tendency of the fuels to produce intake valve sticking is also described. Additionally the chemical and physical properties of the alternative gasolines are reported herein. These results give further insight into the potential advantages and disadvantages of alternative gasolines.