Oil pressure in your 'MINI' motor should be looked at just as critically as you do your blood pressure! If you assume you have good bearings, pump, etc. you might still have low oil pressure just because of a weak spring or a worn and damaged plunger. They are extremely easy to replace and thus should be done at every rebuild. And in fact should be the first thing to check/replace when low oil pressure is noticed! See part# AEA536 for the spring.