I finished building a Cj-7 last year. The Chevy 350 I stuffed in it was also a complete rebuild. The engine is a 1976 four bolt,bored .030 over,flat tops,76cc heads,and a Rhodes flat tappit cam (.450 lift int./exh). I have well over $30,000 dollars invested just in parts. A Jeeper stopped to look at it the other day and asked what I was doing about the SM oil. I go "HUH"? Well that launched a search. I always thought the newest API rated oil was THE BEST, and could be used in ALL engines. When I first started the engine I used Moroso assembly lube on all parts but also used GM break in lube with some Pennzoil 10w-40. After 500 miles I changed and used the same thing. After 1000 miles I used straight Pennzoil 10w-40. I think,after what I have been reading my thoughts on API ratings have been wrong. I only have about 300 miles on this oil change. Did I do any damage to this engine? What should I do different considering the low levels of ZDDP in the big three oils (Pennzoil,Valvoline,Castrol). For now I ordered Redline break in oil, but that will be a week away. What about STP red bottle? I am kinda mad about this whole deal with SM oils considering what I have put in this CJ. Did I also say it took over ten years to build! I also have a 97 Blazer and a 2000 Wrangler both with flat tappits. Have I shortened the engine life span on these? I am just looking for some straight answers.