Factory specified oil grade is 10w30 in the factory service manual for the 2002 Miata. Factory specified oil pressure at 3K rpm is 50 PSI. Lifters are bucket solids. Bypass is above 60 PSI. I have run M1 10w30 EP with no issues but it caused the variable intake valve advance mechanism (engine oil activated) to behave irratically. The M1 0W-40 cured this behavior. The oil pressure gauge in the dash is a fake and only shows the oil is above the oil pressure switch turn on pressure of 10 PSI.
Someday I will install a real OPG.
Someday I will install a real OPG.
