Recently the engine oil pressure light has been coming on at idle after the engine is thoroughly warmed up. Have 120K on engine, Casterol GTX 10W-30, just started doing this after last oil change, oil level is OK.

I temporarily put in a real guage in place of the oil pressure sending switch. The pressure is dropping pretty low at idle, 7 or 8 psi. At 3000 RPM its only a little below service manual minimum, 57 to 60 psi (SM says 63 to 80). Above 3000 RPM it continues to go up - don't remember exactly, but 80 to 90 psi at 4500 to 5000 RPM (didn't take it to redline).

My question is for anyone who has a real pressure guage - what oil pressure do you read at varrious RPM's, such as idle, 3K, and redline? If what I am reading isn't right, any suggestions?

Thanks

 

according to my 95 FSM, at idle it should be at least 10 psi, at 3K it should be between 63.1 and 79.9 - If your level is fine and the pressure is still low you may want to switch to a thicker oil or one that is designed for high mileage engines. The seals in your oil pump may be going bad. Also, I think I remember reading somewhere that the OP light comes on when it is below 11 psi at idle.

 

i recently picked up an oil press. gauge. where did you put your sensor at? i was thinkling of putting mine where that dummy light sensor is on the rear facing side of the oil drain pan . i have an autometer phantom gauge and the threads are npt and the maxima's are bpt i am having a very hard time finding the right fittings to make it work. how did you do yours??

 

Toolrocks - Thanks for the info. Last night I did change out a couple quarts of the 10W-30 for 10W-40 but don't know what difference it made yet. Even if it does help, I never had the OP light come on before, so using heavier oil is just a band-aid and I still don't know what the real problem is.

ronin.... Yes, that is where I connected the guage. I believe the guage threads are 1/8" NPT, so if the OEM sensor is bpt it is apparently close enough match to npt to work.