The ingredients in engine additives are typically identical to the ingredients in synthetic motor oils, making these products no more effective than standard, inexpensive automotive oil. Many engine additives claim to contain friction-reducing materials, but there is no evidence such chemicals reduce engine wear.
The claims of several engine additive manufacturers have gotten them into trouble with the U.S. Federal Trade Commission for making false advertising statements. Engine additive manufacturer Slick 50 was forced to change its advertising language after the FTC found the product had no measurable effect on reducing engine wear. Slick 50 contained polytetrafluoroethylene, commonly known as Teflon, which NASA tests showed to have no protective effect on automotive engines.