Oil Pressure

[cwilson]

I would like to hear what other peoples oil pressure runs at.
After engine is warm, mine runs at only about 15 p.s.i. when idling, and then comes up from there when accelerating. 15 p.s.i. seems low to me - even at idle.....any thoughts?

[Sweet William]

Both my 95's (128k &112k) usualy run around 13psi hot at idle. I posted this same thing a while back, but I think it is read interesting so here it is again...

The wrong viscosity oil can cause a problem also. These motors run hot and viscosity is affected more at temp. extremes.


This is something from bbobynski form another forum about oil pressure. He was an engineer on the Northstar project so I tend to beleive what he says...
"A perfectly good Northstar will idle with 5 PSI oil pressure when it is smoking hot with smoking hot oil.....

Oil pressure is greatly over rated....LOL.... The engine just needs enough oil pressure to deliver oil to the center line of the crank to lube the rod bearings. The minimum oil pressure required is determined by the diameter of the main bearings and the RPM. The oil has to overcome centripital force to reach the center of the crank...that is what oil pressure is for.

Most engines , including the Northstar, will idle with little or no oil pressure. The load on the bearings is so low and the RPM is so low that very little oil flow is needed. Excess oil pressure just takes more energy and fuel....costing fuel economy.

The oil pressure of the Northstar was a bit of a crap shoot when it was being designed and developed. With the expansion of all aluminum main bearing bulkheads and an all aluminum engine and 32 hydraulic tappets there was some consternation about how much oil flow and pump capacity was required...esecially as the engine aged and wore with miles. The pump on the 93 Northstars was pretty big and flowed a lot of oil...even with the large capacity pump , though, the idle oil pressure with the engine smoking hot (like 300 degree oil and 265 degree coolant in Death Valley after pullling a trailer to the top of the pass flat out....LOL) would often be 4-5 PSI. No prob.

As experience was gained with the engine in development and in testing we realized that the oil pump was on the large size for what it needed to be and was costing efficiency and moving a lot of oil around unnecessarily. In 96 the pump was downsized to be closer so as to pump less oil....and improve efficiency.

People are enamored with high flow oil pumps and high oil pressure but it really isn't nescessary. Even the sand rail guys that are spinning the engine 7000 and 8000 RPM use the standard oil pump with no problems. The only issue they have with oiling and bearing problems is climbing hills so steep at max RPM that the pickup sucks air and starves the system...so they run a pressurized oiler system to "make up" oil flow when the pickup sucks air and/or dry sump the sytem. "

[Marc_Aurora_2001]

My 2001 4.0 starts cold with around 69 lbs.,
and when warmed up, runs at 12 - 15 lbs.


_______________

GM!!! BRING BACK OLDS!!!

[RoraStar96]

I get no less then 5 PSI at idle when the engine is at operating temp, I have seen over 15 psi at accel.

[anusemoon83]

at idle i get around 15psi but on highway 70mph i get around 60psi :S

[kev's 96 Aurora]

at hot idle I have low 20's and at hot cruising 70mph I get low 50's. Until I hit around 200 degrees though I have seen it say 65 to 70. I wonder if this is correct.

[BigDaddy Royster]

I idle at around 15psi and on the open highway I get around 60psi crusing at 70mph on my RORA.

[Marc_Aurora_2001]

I have a correction to make to my prior post.
When I mentioned running at 12 - 15 lbs., I
should have said 12 - 15 lbs. at idle. On the
highway, at 65 -70 mph, the pressure is about
65 lbs.


_____________

GM!!! BRING BACK OLDS!!!

[treeboy38]

My 97 gets around 60 psi when I turned the car on. While driving in town it changed between 55-60 psi. Does that mean there is something wrong?

[rodtice]

nope, thats not really high.