Question predicated off that my Subaru is soon to have an EJ20 (JDM) in it. It MAY rev higher on prolonged highway runs; old engine turned at around 2900RPM for my preferred 75MPH on highway (I usually get passed like I am standing still) with 80 being about 3100RPM. Losing a half liter of displacement, I am thinking RPMs will rise.
I do wonder if a 0W-20, 5W-20, 0W-30, 5W-30 oil lubricates "better" than anything heavier than that at higher RPMs, they can really increase once you get flying. 90MPH yields about 4K RPM on old engine and I'm sure many engines rev higher than that.
Everyone says put 5W-30 in a Subaru engine.. even a JDM Subaru?
I do wonder if a 0W-20, 5W-20, 0W-30, 5W-30 oil lubricates "better" than anything heavier than that at higher RPMs, they can really increase once you get flying. 90MPH yields about 4K RPM on old engine and I'm sure many engines rev higher than that.
Everyone says put 5W-30 in a Subaru engine.. even a JDM Subaru?