There was a UOA of a Twin Cam running Kendall 20w50 as well that came back excellent. Around here it is available at any O Reilly auto store and runs over a buck cheaper per quart than the Valvoline VR1. Has the same added zinc(recommended for flat tappet engines right on the bottle) as well as a good dose of moly and titanium ant wear additives. Just has a slightly lower initial TBN than the Valvoline. Might want to look into that as well.