While cleaning out my basement today I came across two quarts of SLICK 50 and three quarts of STP Engine treatment XEP2. I know the Slick 50 is junk, and assume the same for the STP but it seems the main chemical in the STP is "Zinc dialkyldithiophosphate." I've heard good things about zinc, but that it is bad for emissions controls components. Would this stuff be good to use on motorcycle or snowblower motors where there are no emissions controls, or should I just bring this crap to the nearest hazardous waste facility?