Goodbye Crane Flat Tappet. I hardly knew ye.

I don't think synthetic oil would be an immediate cause of a flat cam. I would think it would have something to do with spring pressure and those new 1.6 rockers. I've always used regular oil in all my old stuff. Until I found oil on summit racing called Classic Car and Hot Rod Oil. It's advertised as having proper amounts of zinc for older flat tapped engines. So I don't use an additive anymore.