So let me get this straight...an older engine with a flat tappet cam that is waaay broken in still needs the zinc even if I'm using a full synthetic oil?
All engines with a flat tappet cams were designed with the ZDDP levels at double what they are now. if you use conventional or synthetic, you still don't have the protection that the engineers who designed it counted on.
The higher the spring pressures and the more aggressive the cam lobe, the more necessary it becomes.
this page has a chart from redline: http://www.nitemareperformance.150m.com/ZDDP.html
If you add just a small amount of redline break-in additive to your oil you will bring the levels up to the correct amount.:read2:
