About a 2 months ago I swithed to 20w50 royal purple oil from 5w30. The reason I did this was a oil suppier we have test our thermal oil at work said it would better for bearing life ect. On Friday night I finished installing my new gauges. Boost,oil and fuel pressure along with dual EGT and Dual air fuel. My problem is when I started up the car oil pressure was 87psi at high idle when car came up to temp pressure fell to 47psi at 750rpm. At 2000rpm pressure is 75 when hot. I am scared it is going to blow seals ect.

 

Yes, the oil weight could cause problems especially in your climate. If you were running a race motor that the bearing clearances were a lot looser then your current oil would be ok. On a street engine that has a life expectancy of 100,000 miles the bearing clearance is a lot tighter for longevity. Also, you are wasting power with the thicker oil you don't need anyway. If you are worried about oil consumption then switch to 10W-30 at the most for a non-turbo street application. You also run the risk of a spun bearing because the oil weight.

 

With this motor I have a vortech with 2.87 pulley water/meth ect.and everything else you could put on it. New motor next month 4.15 Brain Crower 8.5to1 coated JE pistons Vortech T trim this is the one I'm realy concerned with. I have never had consumtion problems the oil guy said with forced induction the pressure on the bearing surface can cause 5/30 to be pushed out and not act as a support for the crank ect. If this makes any sense

 

There is some truth to the oil guy's statement. But that's why the bearings have oil grooves. For a motor that generates enough force to actually squeeze a bearing dry then you should run a higher pressure oil pump to over come that force. Using oil to overcome that issue can be risky. Also, it takes a lot longer for the thicker oil to get to operating temp. For a DD that only sees a lot of stop and go, short trips etc. Without the time necessary for the oil to reach it's op temp. It means the acids and moisture in oil does not get burned off and polutes the motor oil.