Ernie,
I am running Royal Purple Racing 21
Oil in my 428FE Engine. Just recently switched from Castroil 20w 50w and will be thrashing the ole hot rod around the Mid America Complex in Omaha next weekend for about three days. Jay Nordstram and Keith Williams have been running Royal Purple for several years now and seem very pleased.
I will change my
oil each day and I should be able to get a pretty good reading from my System One re-usuable filter how the bearings etc are holding up. If I can remember I will post my opinion of how Royal Purple performed when I get back.
Clois