We have dropped the viscosity in the GTO 408 down to Pennzoil Platinum 10-30 from various 5-40/10-40's with excellent results. We have a large oil cooler that keeps the oil at 180f even after hard runs and abuse on Main St. from time to time. OCI's are 500 miles or roughly 15 hours of engine run time.We run dual Amsoil filters so we have roughly an 8qt sump with all the plumbing. Fuel Dilution is 5-20 with some serious TBN/HTHS and am curious if I should give it a shot for 500 miles of pure abuse and see what we get.....any thoughts? Comments? Predictions of equal or better wear/doom? Never thought I'd even consider a 20wt in a 408 Stroker...but I'm leaning towards a test of it.....