if rp is working good why change,its a excellent engine oil,,if wanted try havoline pro-ds 5w-30 ,its got good specs and field proven in many engines,change a couple of times a year and use good filter.
I always assumed that Quaker State Euro, Shell Helix Ultra and Pennzoil Platinum Euro were all pretty much the same (or very similar) full synthetic 5W-40 A3/B4 oils. All SOPUS / Royal Dutch Shell products.
