[long69]

i'm on the fence on this too. like someone in one of the other threads on this subject said (not verbatim) if flat tappets cams required zddp we would see tons of dead ones and all the old cars would not be on the road. last time i was in da pep boise the oil additive section was mighty small and no products promoting anything for flat tappet engines, older engines, nothing to indicate that it was for this purpose- and i was looking for it specifically- although not for very long or closely. i think a good investment (already have one) is a vacuum gauge which should show a change in how well your valve train is working. which mine shows problems, but am i looking at a problem caused by not adding zddp? too early to tell? its only on one cylinder. still have to adj. the valves to make sure its not that. other than that engine runs tits. and is strong