zMAX has had 50 years of ASTM and SAE testing, is it only now in the days of living in a sue happy society, that we hear of problems?
FYI, the testing done initally by the FTC were done without letting the zMAX soak in and they didn't use oil. NEVER, NEVER use zMAX as a substitute for your manufactures recommended requirement for oil. : )AND follow zMAX manufactures directions completely.
PER the FTC dated December 26, 2002, zMAX helps maintain gas milege in newer cars, helps maintain emissions levels in newer cars, helps improve gas milege in older cars and helps improve emissions in older cars---by virtue of its ability to reduce carbon and other engine depostits.
Drive your vehicle for a hundred miles after using the
zMAX and then change your oil...you'll notice the blackness..that is the carbon that is giving you poor milege, worse emissions and more. If you have a problem after that, your engine was not dimensionally correct to begin with.
Keep your engine (internally) clean enough to eat off of and you will have a more durable engine.