Well the product that doesn't work has caused such a reduction in oil flow to the top end (lifters) 3,100 kms into this first 10,000 km clean phase I have booked a filter change for this Wednesday. I have 18 oz of RX in a 4.2 quart sump, (overbasing RX) and the noise indicates that maybe my 10,000 km clean is a optimistic. Probably have to cut it back to 8,000 kms (5,000 miles) or even 6,000 kms (4,200 miles) unless I cahange filters regularly, but they are cheap. It's just great having three vehicles to experiment with.