guys-----i hate to bring bad news to what seems to be a simple subject BUT there is a serious misunderstanding displayed in this thread------i do not have time to go into detail tonight but i want to briefly touch on clarifying the error-----If for a moment we can agree that the long proven additive ZDDP is good for our cars it will let me get to the real subject-------ZDDP is a combination of zinc, sulfur, and phosphorous--------this recipe of ingredients are combined and "cooked" in a chemical process that results in ZDDP------the process is so nasty and dangerous that it is no longer done anywhere in the United States and it must be done BEFORE the zinc and Phosp is added to the oil------like a cake that has ingredients of flour, eggs, sugar and baking soda the ingredients of ZDDP must be combined and processed in a certain way (and quantity) or they don't result in ZDDP-----imagine a bowl where eggs, sugar, baking soda and flour were just thrown in---------it would have the same ingredients as a real cake but i can guarantee you which would make the best birthday cake!!!!-------testing your oil before you put it in the engine doesn't guarantee it has real zddp even if all the ingredients are there in the proper amount------if the ratios are properly balanced it is possible that it does--------- but it is no guarantee----------furthermore testing your oil AFTER it is removed from service tells even less since zinc content actually goes up as a by product of use and zddp starts depleting the moment you start your engine--------a simple chemical analysis will not actually tell if you have real ZDDP-------the chemical analysis of a living and dead horse will look identical-------i don't mean to sound trivial but a lot is taken for granted when we trust a simple chemical analysis like is provided for less than $100 bucks-----------i'll try tomorrow afternoon to touch on this subject in real detail and cover what is the difference in real zddp and just zinc and phosphorous and what is required to actually measure the quantity of zddp in motor oil....................RC