Oil & Filters, the never ending opinion/story.
I have used Synthetic, 5W30 in my 04 Chev Avalanche, 02 Camaro LS1 & most recently in my 94 Trans Am LT1 without issue. The 02 Camaro LS1 has been bone dry wrt, oil leaks for the 8 years I have owned it. The Avalanche just started an oil leak last year, but it's even too small to find. I use only WIX filters. On my GN & TTA I have been using Royal Purple & WIX. Both cars have a very small leak, not even enough to get concerned over. Have had tons of old cars over the years, sooner of later they all leak something, that is a fact.
66 GTO gets Shell 10W40 Dino & the rear main leak like a sieve, one of these days I have to pull the motor & replace every gasket & seal.