Better oil flow is advantageous. Pressure would be the measure of resistance to flow. Usually when people want better flow in any engine they use a higher volume oil pump and or ream out any obstructions in the flow path. You can also gain by using a good synthetic oil that is only as "thick" as needed.
Excessive oil pressure can blow seals, especially the rear main seal. Decades ago, NASCAR had problems with the cars blowing engines in the early laps. They found that it was due to not warming the engine up well enough and the high oil pressure was blowing the seals, causing bearing failure. That was in the days when single weight oils were more common. It's also part of the reason for the warmup laps.
You could upgrade to the 3.4 oil pump which is a little higher volume pump, but if you're using the 2.8 oil pan, you'll have to notch out the baffle to clear the pickup.
[This message has been edited by fierofool (edited 07-08-2014).]
We used to think more is better, but 10psi/per 1000 rpm is all thats needed. A high volume high pressure pump on 10-30 oil requires 5 hp to drive, and more load on the cam gear and distributor gear.
what you said just summed it up. That's what Smokey Yunik said "10 lbs per 1000 RPMs". BUT, my 2.5 has 30 psi at Idle Cold, and after it's at 180 it's 20 and only 25 at 3000 RPMs ! The engine only has 3-4k miles on it. (Stock Oil pump). Is there a HV or HP PUMP "available" for a 2.5 ?? Or a high pressure relief SPRING for it ?
what you said just summed it up. That's what Smokey Yunik said "10 lbs per 1000 RPMs". BUT, my 2.5 has 30 psi at Idle Cold, and after it's at 180 it's 20 and only 25 at 3000 RPMs ! The engine only has 3-4k miles on it. (Stock Oil pump). Is there a HV or HP PUMP "available" for a 2.5 ?? Or a high pressure relief SPRING for it ?
what you said just summed it up. That's what Smokey Yunik said "10 lbs per 1000 RPMs". BUT, my 2.5 has 30 psi at Idle Cold, and after it's at 180 it's 20 and only 25 at 3000 RPMs ! The engine only has 3-4k miles on it. (Stock Oil pump). Is there a HV or HP PUMP "available" for a 2.5 ?? Or a high pressure relief SPRING for it ?
You don't need a HV pump for the 2.5. In fact, when you put a high volume pump on, you risk shearing the pin that holds the oil pump drive gear to the oil pump driveshaft. If you use the correct weight oil, you'll get sufficient flow and won't need a higher pressure relief spring.
If you feel desperate to have a higher relief pressure at the pump, then you can knock out the roll pin and shim the existing spring with a couple of small washers. Do not over-do it.
A higher pressure relief spring isn't going to fix anyone's low oil pressure issues.
The only thing that spring does is limits the upper end of what pressure the pump will be able to build if the conditions are right. But once the oil is warm and the RPMs are down, the pump simply isn't able to build anywhere near the limit pressure, so that spring isn't a factor.
Don't think of the spring as a regulator. Think of it as an upper limit safety blow off valve instead.
My point being, only 3-4k miles, new crank, bearings etc , but "10 PSI per 1000 rpms," and this is 25 at 4K RPMs, should be 40 PSI.. Still has the original oil pump. I know it's not going to blow up, it never gets driven hard. just wondering.
On my 2.5 the oil pressure is 30psi at idle and at 60 mph cruising speed is 45ps in fifth gear. I am running 10w-30 dino oil. Should I switch to a lighter weight oil? The car has 118k miles on it and has never had synthetic in it so I don't want to put any in at this point. Thanks
On my 2.5 the oil pressure is 30psi at idle and at 60 mph cruising speed is 45ps in fifth gear. I am running 10w-30 dino oil. Should I switch to a lighter weight oil? The car has 118k miles on it and has never had synthetic in it so I don't want to put any in at this point. Thanks
If those are at warm temps (after driving about 20-30 mins and your temp is around 190) you definitley could, 5w30 is factory recommended.
[This message has been edited by 2.5 (edited 07-11-2014).]
From what I've seen most if not all GM pumps were made from cast aluminum which wear out very quickly on the inside, a good replacement pump (Melling) will be cast iron. I think you should have put in a new pump.
My point being, only 3-4k miles, new crank, bearings etc , but "10 PSI per 1000 rpms," and this is 25 at 4K RPMs, should be 40 PSI.. Still has the original oil pump. I know it's not going to blow up, it never gets driven hard. just wondering.
When you had the engine apart did you check the oil pump clearances to see if everything was in spec?
From what I've seen most if not all GM pumps were made from cast aluminum which wear out very quickly on the inside, a good replacement pump (Melling) will be cast iron. I think you should have put in a new pump.
Have you disassembled a 2.5 before? I have never seen an aluminum 2.5 oil pump.
A higher pressure relief spring isn't going to fix anyone's low oil pressure issues.
The only thing that spring does is limits the upper end of what pressure the pump will be able to build if the conditions are right. But once the oil is warm and the RPMs are down, the pump simply isn't able to build anywhere near the limit pressure, so that spring isn't a factor.
Don't think of the spring as a regulator. Think of it as an upper limit safety blow off valve instead.
