Oil pressure?
Thread Starter
Racer
Joined: Oct 2021
Posts: 436
Likes: 15
From: Maryland
Oil pressure?
Hello, I have an 82 with the following readings for oil pressure:
Cold:
35psi @ 1000rpm
40psi @ 1300rpm
45psi @ 2000rpm
Warm:
10psi @ 600rpm
35psi @ 2000rpm
Are these readings ok? By that I mean, are they enough to at least not damage the engine? I run Brad Penn 10w-30. Thanks
Cold:
35psi @ 1000rpm
40psi @ 1300rpm
45psi @ 2000rpm
Warm:
10psi @ 600rpm
35psi @ 2000rpm
Are these readings ok? By that I mean, are they enough to at least not damage the engine? I run Brad Penn 10w-30. Thanks
Melting Slicks
Joined: Oct 2010
Posts: 2,276
Likes: 337
From: "ɹǝpunuʍop", Adelaide, South Australia
usual rule of thumb for a SBC is 10psi per 1000rpm
but i would run mine higher at idle for safety... 20 to 25 with a Hydraulic cam so lifters wont make any noise.
but i would run mine higher at idle for safety... 20 to 25 with a Hydraulic cam so lifters wont make any noise.
Race Director
Joined: Nov 2006
Posts: 13,177
Likes: 7,780
From: Sunshine Coast, Queensland, Australia
2025 C3 of the Year Finalist - Modified
2024 C3 of the Year Finalist- Modified
2022 C3 of the Year Finalist - Modified
Cruise-In VIII Veteran
I've had my SBC in my Vette for a long, long time now.
I've never run such a light oil.
I have always had 40 PSI at idle.
Changed a oil pump not long ago. Still 40 PSI at idle, cold or hot.
I've never run such a light oil.
I have always had 40 PSI at idle.
Changed a oil pump not long ago. Still 40 PSI at idle, cold or hot.
Safety Car
Joined: Oct 2007
Posts: 4,203
Likes: 1,074
From: South Florida
Higher pressure = less flow from the pump. Using a thicker oil will create more pressure on a gauge but reduce oil flow through the engine.
Similar with fuel pumps, higher pressure = less fuel flow. I always reduce fuel pressure as much as possible.
Same thing in heart systems, lower blood pressure = superior circulatory system, reduced stress. You don't want a high pressure if you don't need it.
Some systems needs a high pressure so it depends.
In this case, I would say the pressure reading is fairly normal for an SBC. Modern LS engines tend to keep higher baseline oil pressures near 38psi I've noticed but the old SBC I can always remember 20 years ago seeing 10psi at idle and thinking "thats fine".
I think you are fine with the numbers you reported op. But you should also keep an eye on the pressure and using a mechanical gauge to always be aware of the oil pressure.
Similar with fuel pumps, higher pressure = less fuel flow. I always reduce fuel pressure as much as possible.
Same thing in heart systems, lower blood pressure = superior circulatory system, reduced stress. You don't want a high pressure if you don't need it.
Some systems needs a high pressure so it depends.
In this case, I would say the pressure reading is fairly normal for an SBC. Modern LS engines tend to keep higher baseline oil pressures near 38psi I've noticed but the old SBC I can always remember 20 years ago seeing 10psi at idle and thinking "thats fine".
I think you are fine with the numbers you reported op. But you should also keep an eye on the pressure and using a mechanical gauge to always be aware of the oil pressure.
Race Director
Joined: Jul 2015
Posts: 13,082
Likes: 3,399
From: SW Florida.
in a fuel pump you need flow. in an oil pump you need pressure. every bearing and lifter bore is a leak. as the engine wears the bearings get a bit larger and leak more. unfortunately the last thing that gets oil is the rod bearings. the only way to get oil there is through the groove in the mains full of pressurized oil that is leaking out the sides of the mains at the same time. they want and need pressure. as engine wears it loses oil pressure. heavier oil and new oil pumps help to up the oil pressure in a tired engine. eventually it will need new bearings at the least. but that may be 50 to 100k miles farther down the road.
Safety Car
Joined: Oct 2007
Posts: 4,203
Likes: 1,074
From: South Florida
in a fuel pump you need flow. in an oil pump you need pressure. every bearing and lifter bore is a leak. as the engine wears the bearings get a bit larger and leak more. unfortunately the last thing that gets oil is the rod bearings. the only way to get oil there is through the groove in the mains full of pressurized oil that is leaking out the sides of the mains at the same time. they want and need pressure. as engine wears it loses oil pressure. heavier oil and new oil pumps help to up the oil pressure in a tired engine. eventually it will need new bearings at the least. but that may be 50 to 100k miles farther down the road.
Race Director
Joined: Jul 2015
Posts: 13,082
Likes: 3,399
From: SW Florida.
i had a jag XJ6. big long steel crank. eats the main bearings. i was running a mix of STP and 70w racing oil. i had 40 lbs of oil pressure at idle cold. i had 6 lbs of oil pressure at highway speed warmed up. it didn't knock. i eventually junked it. this is an extreme version of main bearing wear, but a racing engine and a worn driver are 2 completely different animals with completely different needs.
Safety Car
Joined: Oct 2007
Posts: 4,203
Likes: 1,074
From: South Florida
i had a jag XJ6. big long steel crank. eats the main bearings. i was running a mix of STP and 70w racing oil. i had 40 lbs of oil pressure at idle cold. i had 6 lbs of oil pressure at highway speed warmed up. it didn't knock. i eventually junked it. this is an extreme version of main bearing wear, but a racing engine and a worn driver are 2 completely different animals with completely different needs.
Its an awareness issue, not an engine issue. A heavy weight oil will function as a light weight oil with enough temperature input.
It comes down to knowledge of viscosity and the engine's needs when we are discussing modern engines with tight clearances.
Older engines- all bets are off. Large sloppy clearance can deal with a heavy weight oil especially with high flow oil pump.
which brings up another valid awareness issue: the oil pump is volumetric with respect to rotational flow rate. It doesn't flow extra oil when the oil is thinner. Thin lightweight oil only flows through oil orifices faster because of reduced friction.
I appreciate the discussion, thats all really. I just like to discuss these issues. I am not argue with you or disagree with you. Its just for fun. Entertainment. And somebody can learn something.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski
Advanced
Joined: Aug 2019
Posts: 53
Likes: 24
From: Indiana
My '82 runs over 60psi at 1500 rpm and never under 40psi at 600 rpm. This seems high for an engine with 85,000 miles on it. Accordingly, I have never put much trust in the gauge in terms of what the pressure actually is. I think of the gauge as useful mostly for comparison purposes. In other words, if I have only 40psi in my vette at 1500rpm, I would think I have something going wrong -- regardless of what my actual pressure probably is, as that would be well below my normal.
1967 Pedal Car Champion
Joined: Mar 2020
Posts: 9,026
Likes: 4,174
From: US-PNW
Hello, I have an 82 with the following readings for oil pressure:
Cold:
35psi @ 1000rpm
40psi @ 1300rpm
45psi @ 2000rpm
Warm:
10psi @ 600rpm
35psi @ 2000rpm
Are these readings ok? By that I mean, are they enough to at least not damage the engine? I run Brad Penn 10w-30. Thanks
Cold:
35psi @ 1000rpm
40psi @ 1300rpm
45psi @ 2000rpm
Warm:
10psi @ 600rpm
35psi @ 2000rpm
Are these readings ok? By that I mean, are they enough to at least not damage the engine? I run Brad Penn 10w-30. Thanks
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,171
From: Hermosa
Conventional multi wt oils use polymers to thicken the oils. These polymers shear after some use and fail to thicken the oil sufficiently at temperature and you’re left with the base wt oil. So 10w-30 becomes straight 10wt after a fashion. This will lead to lower oil pressure due to lower viscosity.
if you use a synthetic oil that is a base wt oil of the higher viscicity that flows as good as the lower viscosity rating.
So a 0w-40 synthetic performs as a 40 wt oil at operating temperature until the change interval. Yet it flows like a 0wt oil at start up.
I would use a synthetic oil vs a conventional. If you need the zinc Mobil one 0w-40 full synthetic has 1100 ppm.
Mobil one 15-w50 full synthetic has 1850ppm zinc.
your solution is likely to run a thicker oil. Worth a shot.
if you use a synthetic oil that is a base wt oil of the higher viscicity that flows as good as the lower viscosity rating.
So a 0w-40 synthetic performs as a 40 wt oil at operating temperature until the change interval. Yet it flows like a 0wt oil at start up.
I would use a synthetic oil vs a conventional. If you need the zinc Mobil one 0w-40 full synthetic has 1100 ppm.
Mobil one 15-w50 full synthetic has 1850ppm zinc.
your solution is likely to run a thicker oil. Worth a shot.
Race Director
Joined: Jul 2015
Posts: 13,082
Likes: 3,399
From: SW Florida.
synthetic flows better and has higher film strength whether flowin or just sitting there. the downside is it flows good past seals, rings, etc. so the oil is better for a tired engine but it will use more oil.
Thread Starter
Racer
Joined: Oct 2021
Posts: 436
Likes: 15
From: Maryland
Thank you everyone. Seems like common consensus is the readings are not to be concerned over, just to check the readings with a mechanical gauge and perhaps switch to a slightly thicker oil. Will do. I should mention that I dont race this car, nor really take it past 2500 rpm.