I bought my GS in 96 with 33k on it. Changed the oil religously but todays oil change was the first one I added ZDDP too. The car had 39k on it now, never raced, just a cruiser. Should I be concerned about the lack of zinc over those years??? When did oil mfrs take out the zinc?? o No: Thanks!!
If you have stock valve springs I wouldn't be concerned it is good that you are running it now. Jamie
If you got away with it you are lucky.... the oil changed shortly after all the factories went to roller cams... i will not change oil without using zinc too.
I read recently that there's enough zinc in most oils to allow a well broken in engine to survive, but I'm not sure how true that is. My Electra has run ZDDP in it since I built it 2 years ago, and there haven't been any problems, so I'll continue to run it. Just as an example; a buddy of mine owns an old T-Bird, and when he put zinc in it the mild lifter tick he used to hear disappeared; -take it for what it's worth...
