FWIW I just threw a stock LLY engine back in my truck for right now. Stock as in like stock single turbo, stock intake manifold, etc.
This engine has GREAT oil pressure. Like almost 30psi HOT at idle, and over 60psi cruising at 80mph. My factory original engine had OK oil pressure. The first built engine had good oil pressure, but not as good as this current one. The stock LBZ I had in there for a while had friggin awful oil pressure...thats why I started this thread. Even with 20w-50 it would be like 15-16psi hot at idle and when towing heavy in the hot weather, maybe 35psi on the highway.
This confirms my opinion that LLY's are the best...
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That (the stock LBZ) was one of those GM test engines. When I took it apart the bearings looked worse than 300k mile duramax's ive torn down (that LBZ that broke the crank had test time at GM, and then I put 50k on it), there was a broken off dipstick in the oil pan, none of the main caps were torqued equally, rod bearings didnt look good either.
Ben