Originally Posted By: Mackelroy
When I was in Automotive school, we took apart an engine full of sludge.Instructor said, that's what happens with STP oil treatment, all that zinc doubles what you already got, and creates deposits.
Well, by using this ZDDP additive, the only way you could double the level already in the sump is if one were using something that wasn't even close to current API specifications, much less the older, higher ZDDP ones.
In just about any current oil on the market (or even within the last fifty or sixty years), this additive would DECREASE the ZDDP concentration. What a terrible, useless product. If my oil isn't thick enough, I'll buy a thicker grade, like an HDEO. If my oil doesn't have enough ZDDP, I'll buy an HDEO, or at least a proper additive.
The only conceivable use for this product in my view is if someone had a totally messed up carb that was just washing the cylinders, causing huge fuel dilution, and one had a container of this handy and couldn't do an oil change. Rolling it off a cliff would probably be kinder than using this stuff, though.