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PostPosted: Tue Sep 01, 2015 9:13 pm 
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So, maybe I'm not used to it but is it normal for the oil pressure gauge on these cars to move slightly?

When I idle it sits just under 40psi. When I'm at 1000RPM it sits at 40psi and anything above that (normal driving, 40-45MPH) it sits just above 40psi. It never goes more than a eighth in either direction from the center.

I was just wondering because my Grand Prix would just sit in one spot and wouldn't move (as far as I knew) under any RPM. My old tractor will change pressure with RPMs and I know increased RPMs = increased pressure so it seems like a silly question (even to me), but with all the quirkyness of the Northstar and the fact I'm new to the engine makes me want to ask questions about every little detail.

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PostPosted: Tue Sep 01, 2015 10:02 pm 
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It is normal for oil pressure to fluctuate. Some cars dumb it down so that the gauge sticks in one spot as long as it's in range, where others actually display what is happening.

In the Regal, the gauge has a midway point at 40PSI, and max at 120 PSI. I have no idea what spots on the gauge mean what, because it seems like the first quarter of the gauge is like only linear for 3/4 of the gauge.

It could also be that the GXP does dumb it down, and the stepper motor is starting to go in the cluster. The pressure rule for the 3800 is minimum 10psi per 1k RPM, but I don't know what it is for the Northstar.

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PostPosted: Tue Sep 01, 2015 10:25 pm 
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Sounds like it's all normal. Mine moves all over the place depending on engine speed, temperature, etc. As mentioned above though, the pressure rule for most motors is 10psi of pressure per 1k RPM.

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PostPosted: Wed Sep 02, 2015 12:02 am 
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Uh, yea...

Oil pressure minimum at idle should be ~5psi
Oil pressure minimum at 2,000 rpm should be ~35psi

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PostPosted: Wed Sep 02, 2015 12:37 am 
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RJolly87 wrote:
It is normal for oil pressure to fluctuate. Some cars dumb it down so that the gauge sticks in one spot as long as it's in range, where others actually display what is happening.


Thats what I thought. My dads Lexus, step-sisters Corolla, and my old GP all didn't fluctuate. This is the first car I've driven that I've actually see do it so I was just curious. I know as the engine warms the pressure should drop some due to lower viscosity.

CMNTMXR57 wrote:
Uh, yea...

Oil pressure minimum at idle should be ~5psi
Oil pressure minimum at 2,000 rpm should be ~35psi


The gauge is weird because half way is 40psi but max is 120psi. At 1000-1500RPM it sits on or just past the 40psi mark, but I can't really tell what that is.

Come to think of it, I've never actually watched it while accelerating into the 3000-4000 range (too busy watching the road). I'll pay more attention to it going to work tomorrow.

Thanks for the replies guys!

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PostPosted: Wed Sep 02, 2015 10:58 am 
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What I posted is the "minimum" at those RPM's.

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Summer Toys: Combined 827 RWHP / 877lb/ft RWTQ
2004 Pontiac GTO: Impulse Blue Metallic/Black/M6: lots 'o mods, 415 RWHP / 405lb/ft RWTQ!
2006 Cadillac STS-V: Light Platinum Metallic/Light Gray/A6 - Spectre CAI, Magnaflow exhaust, Speed Inc. tune, 412 RWHP / 472lb/ft RWTQ

Daily Drivers:
2015 Chrysler Town & Country Limited Platinum: Mommy's NEW RGC
2007 Chrysler Town & Country Limited: Daddy's beater affectionately called the Rolling Garbage Can or "RGC" for short
2009 Pontiac G8 GT: L76, Sport Red Metallic
2009 Chevrolet Impala SS: LS4 V8, Victory Red
1999 Chevrolet Suburban: Sunset Gold Metallic - Daddy's winter beater and plow truck


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