normal oil pressure for a C5 corvette
Thread Starter
Heel & Toe
Joined: Mar 2021
Posts: 15
Likes: 0
From: Idaho
normal oil pressure for a C5 corvette
ok so ive been noticing my 1998 C5 is reading really low oil pressure at low rpms. when I fire it up after its been sitting for a while or over night it reads 40-45 psi. after letting it warm up it drops. going 80 mph on the freeway the psi sits at 40ish with the temps at 190. driving around town at around 35mph it sits at 30-35 psi with temps ranging. its at idle and at red lights where I get nervous because it drops down to the lower 20s. last week it hit 90 degrees here in Idaho and at a red light my psi was reading 20!! I don't remember seeing it ever that low. today it was cooler at 77ish and I was seeing 23psi at red lights with the temps at around 200-210. I've read the temps are normal but idk about the oil pressure. I got the car as a project car and the oil pressure sensor wasn't working. I replaced it recently and im just wondering if these are normal since I have no experience owning corvettes before. the car has 125,000 miles on it and im running 5w30 mobile 1 full synthetic. I researched online and found some people saying its ok and others saying I should be worried. its stressing me out not knowing if its ok or not.
Thread Starter
Heel & Toe
Joined: Mar 2021
Posts: 15
Likes: 0
From: Idaho
Race Director
Joined: Oct 2004
Posts: 12,864
Likes: 4,668
Don't worry about it. I know guys who've raced cars with 15psi at idle, and only 40psi at 7,000rpm. They never had any issues, at least with the motor. I have piston squirters in my built LS7 in my C5, and even with the Hi volume 10296 Melling pump, I'm at around 25psi at 850rpm idle when oil is at 200°F. Sure, you're a bit on the low side. IIRC, the factory low oil pressure warning comes on@7psi. So your 3x that. Relax, and enjoy!!
Race Director
Joined: Oct 2004
Posts: 12,864
Likes: 4,668
I thought the warning came on at 7psi. Regardless, 6 or 7, I agree with you that either is lower than anyone would want to run the engine with. Have to wonder why GM has the warning that low????
Burning Brakes
Joined: Aug 2002
Posts: 1,190
Likes: 56
From: Milan Indiana
I asked this question on another forum as my car ,like the OP has high miles and similar pressure. he suggested, as a mechanic, to switch to a 40 weight 5 or 10 and it should help the oil pressure. he said bearing wear would be less noticeable then. The numbers we have on ours is not at a dangerous level Just old motors. Hope he is right!
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Race Director
Joined: Oct 2004
Posts: 12,864
Likes: 4,668
I asked this question on another forum as my car ,like the OP has high miles and similar pressure. he suggested, as a mechanic, to switch to a 40 weight 5 or 10 and it should help the oil pressure. he said bearing wear would be less noticeable then. The numbers we have on ours is not at a dangerous level Just old motors. Hope he is right!
Drifting
Joined: Jul 2015
Posts: 1,844
Likes: 375
From: San Jose, CA
Low 20s at hot idle isn't too concerning to me. These engines tolerate a fairly wide range of pressures. And yeah, as the engine wears and the oil pump wears and clearances get every so slightly larger over time, your pressure will drop a bit.
Some oils, despite being the same rated viscosity, also result in a different idle pressure. For example, Amsoil's 5W30 signature reads about 3-4 PSI lower, at hot idle, in my car, than the standard Mobil 1 5W30. Motul's 300V is likely to be another several PSI lower, but I am not made of money
You can always run a 40-weight oil if it really bothers you... but until you tell us what pressures you're seeing at (roughly) 2k, 3k, 4k, 5k RPM, we're missing info. With the info we have, I agree with the consensus of - don't worry about it.
Some oils, despite being the same rated viscosity, also result in a different idle pressure. For example, Amsoil's 5W30 signature reads about 3-4 PSI lower, at hot idle, in my car, than the standard Mobil 1 5W30. Motul's 300V is likely to be another several PSI lower, but I am not made of money
You can always run a 40-weight oil if it really bothers you... but until you tell us what pressures you're seeing at (roughly) 2k, 3k, 4k, 5k RPM, we're missing info. With the info we have, I agree with the consensus of - don't worry about it.
Safety Car
Joined: Jan 2012
Posts: 3,956
Likes: 520
From: Da U.P.
Low 20s at hot idle isn't too concerning to me. These engines tolerate a fairly wide range of pressures. And yeah, as the engine wears and the oil pump wears and clearances get every so slightly larger over time, your pressure will drop a bit.
Some oils, despite being the same rated viscosity, also result in a different idle pressure. For example, Amsoil's 5W30 signature reads about 3-4 PSI lower, at hot idle, in my car, than the standard Mobil 1 5W30. Motul's 300V is likely to be another several PSI lower, but I am not made of money
You can always run a 40-weight oil if it really bothers you... but until you tell us what pressures you're seeing at (roughly) 2k, 3k, 4k, 5k RPM, we're missing info. With the info we have, I agree with the consensus of - don't worry about it.
Some oils, despite being the same rated viscosity, also result in a different idle pressure. For example, Amsoil's 5W30 signature reads about 3-4 PSI lower, at hot idle, in my car, than the standard Mobil 1 5W30. Motul's 300V is likely to be another several PSI lower, but I am not made of money
You can always run a 40-weight oil if it really bothers you... but until you tell us what pressures you're seeing at (roughly) 2k, 3k, 4k, 5k RPM, we're missing info. With the info we have, I agree with the consensus of - don't worry about it.