Question: Oil pressure in an old 1988 Motor?

[killain]

I'm having some work done on my old Vette, and I always wondered about the reading, so we hooked up and manual gauge and the temps were:

Cold start on 10W/30 is 39 PSI in gear : 37 and with the A/C on it's @ 35psi

Warmed up it is at idle 24 in gear 23 and with A/C running in gear it's @ 23

Warmed up at idle out of gear and A/c turned off, it's running @ 625 rpm with 23psi ?

And Reved up in park to 3500 rpms it 39 again

This is with all done with a new AC Delco oil filter and 5 quarts of Mobil's " Super" "High Mileage" 10W/30. I don't have an past knowledge of any synthetic oil ever being used in the engine so not wanting to create a problem I went with 'Dino' conventional oil.

Do these reading look normal to you gents ? Is this normal oil pressures reading ? Car is almost silent at idle. What do you think ?


Oh, The mileage is 112.590

 

[Hib Halverson]

For an late 80s L98, those pressure readings are normal for a 10W30.

The cheap trick is to drop the oil pan, drop the oil pump, drive out the pin holding the pressure relief valve spring and replace it with GM PN 3848911.

With that, your oil pressure will be about 60-70 psi hot at high rpm.

If you get the pump out, take it apart and find that at miles 112,590-mi, it's showing it's age, replace it with an 2G LT1 pump PN 12555884.

 

[killain]

Oil Pressures ?

For an late 80s L98, those pressure readings are normal for a 10W30.

The cheap trick is to drop the oil pan, drop the oil pump, drive out the pin holding the pressure relief valve spring and replace it with GM PN 3848911.

With that, your oil pressure will be about 60-70 psi hot at high rpm.

If you get the pump out, take it apart and find that at miles 112,590-mi, it's showing it's age, replace it with an 2G LT1 pump PN 12555884.

Thank you Hib,
I was hoping you'd look in on me, I think that is excellent advice and I'll do it towards the end of the summer when I pull the heads for a rebuild. You are truly a godsend for this site and community. You've forgotten more than any of us will ever learn on our own. Thank you again !

I live in SE Pennsylvania, should I run 10W/30 or stick with 5W/30 ?