We have two 604 engines. One two years old and one with two races on it. I see you recommend the Joe Gibbs oil. Both these motors have ran on the Mobil 20w 50 that GM calls for on the engine. Changed oil and filter every four races. My question is if I changed over to Joe Gibbs is there anything I need to do besides just drain oil and change filter and what weight Joe Gibbs you recommend? Or should I just keep running on Mobil 1? We have not seen any wear on or other two 604 engine's. The only problem I see with the 604 is the retainers breaking (bottom washer under valve spring) and have found some of the keepers cracked. We run UMP and they said we had to run the GM keepers. I was hoping they would let us put a good steel keeper in them but they said no. Any help on this would be appreciated. One more thing what RPM and timing do you recommend?
Thank You
Brad Denney
Thank You
Brad Denney
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