Borderline Low Oil Pressure, Normal? - Page 3 - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


1992-1999 Series I L27 (1992-1994 SE,SLE, SSE) & Series II L36 (1995-1999 SE, SSE, SLE) and common problems for the Series I and II L67 (all supercharged models 92-99) Including Olds 88's, Olds LSS's and Buick Lesabres Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.

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Old 05-14-2007, 08:10 AM   #21
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I've had two motors recently with pressure that dropped like that.

Being that you aren't seeing a self destruct sequence, that'* good. It'* quite possible your pressure sender is a lemon, or that your bearings are worn as mentioned.

Have you considered an oil pressure kit from Intense or ZZP? It is fairly easy to install and brings pressure up about 5lbs or so. I'd have a better reference for you, but my pressure sender doesn't like me. (New Napa one in car, car at shop).
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Old 05-14-2007, 12:26 PM   #22
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Quote:
Originally Posted by Hans
I dont fully understand the correlation between trans temp and oil pressure but its related is all I can tell.
First, the hotter the oil, especially at temperatures above the thermostat set point (180-240F), the thinner the oil and the lower the oil pressure. This is because thinner oil flows more quickly and with less resistance around the bearings in the engine. Even though multi-viscosity oils are supposed to get thicker as they get hotter, and that may be true comparing flow at 0*F to flow at 160*F, I have not observed any engine running multi-viscosity oil whose oil pressure increases between 180 and 240F. Rather, I have consistently observed the opposite.

The transmission fluid is cooled in the radiator giving up its heat to the coolant that circulates to the engine. So, the hotter the transmission fluid, the hotter the coolant, and the hotter the engine. That'* why a separate transmission cooler lowers engine temperature. The separate cooler is able to remove heat from the transmission fluid without transferring much of it to the engine coolant circulating through the radiator.

So, cooler transmission fluid -> cooler engine coolant -> cooler engine temperature -> thicker oil -> higher oil pressure.

Just to be clear, we are talking about engine temperatures above the set point of the thermostat and engines whose cooling system capacities exceed the engine'* cooling needs.
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Old 05-14-2007, 01:13 PM   #23
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That looks good:
http://www.intense-racing.com/Mercha...egory_Code=PBF

http://www.zzperformance.com/grand_p...=219&catid=109

Hans, are your PCM'* configured to kick on fans for a 180 Tstat? I am thinking of getting a PCM with fan points adjusted to see if by keeping it cool that way, I can increase the PSI a little bit.
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Old 05-14-2007, 01:42 PM   #24
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If your car will currently make 60 psi on cold start up, it is hard for me to understand how a stiffer relief valve spring will improve the low oil pressure you are seeing at 200*F. If your current spring has weakened so that the car can't ever get to 60 psi, but bypasses instead, yeah, a new spring may help some. But unless the current spring and piston are so worn that oil is bypassing continuously, these new parts are not going to help the problem much, if at all.

Seems to me these parts are designed for guys with tight engines who want to increase the pressure and flow of oil to their bearings. They won't do a thing for worn bearings.
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