In Reply to: Lower oil pressure with heavier weight oil? What’s going on? posted by JohnB on March 05, 2018 at 11:15:03:
My guess - funky gauge. Grade 20W50 is going to have a higher viscosity at all temperatures and there should be no decrease in oil pressure at any RPM. The higher idle oil pressure is consistent with that. Get yourself a good mechanic's oil pressure gauge and see what it tells you.