Amsoil 10W-30 ATM was the #1 performer in my 2009 GT500. It held the rated viscosity every sample.
SR, you may want to check out this thread if you haven't already. The samples at the top of the chart are all mine.
GT500 UOA thread
SR, you may want to check out this thread if you haven't already. The samples at the top of the chart are all mine.
GT500 UOA thread