[tirebird]

Shortly after rebuilding my LS6 in January of 2006, I contacted the CompCams which provided the flat tappet hydraulic bump stick for my engine. I, like a lot of people, heard horror stories about the new oil back then. The CompCams tech told me that just about all the cam failures they've seen happened at break-in. He couldn't recall anyone ruining a flat tappet cam after break-in. I don't know if that's true now or among all cam manufacturers but it's certainly true with my cam. I broke in the engine using Castrol 20w-40w for the first 3k,.changing the oil twice during that time. Since then, with about 10k more mileage on the car, I've used 15w-50 Mobil One. No problems with the cam and the engine doesn't burn any oil. I questioned Mobil 1 about the amount of ZDDP in their oils and received the following response in April of last year.

"Mobil1 MX4T 10W40 and Mobil1 V-TWIN 20W50 motorcycle motor oils, Mobil1
15W50 Extended performance and Mobil1 5W40 diesel motor oils contains
the higher levels of zinc and phosphorous for your cams. The new energy
conserving motor oils do have reduced levels of zinc/phos however, they
typically do not have any adverse effects on cams unless you are
running
higher valve spring pressures. I would suggest you stick with the
product listed above if you are concerned about the phos/zinc issues."