[markpj23]

Had been flying on idiot lights thus far but now I have a gauge set for temp, volts and oil pressure. First ride today with the gauges.

Oil pressure started out around 55 psi then with the engine warmed up to 190 the oil pressure at idle would drop to 20 psi. Still 40 - 45 psi above idle.

Is this OK? I know nothing about the engine history except that it's an early 70s YT block with 6X heads. Had the valve covers off yesterday and it looks pretty clean up top anyway.

[grandam1979]

Sounds about right for a stocker.

[steve25]

Your fine with hot PSI numbers like that. So sleep well at night and fear not when your foot is on the floor mat!
I once had a 400 who’s pump had the bypass held unseated by a spec of broken off silicone sealer.

This started in the beginning of winter and I did not want to pull the motor down until spring time if I could avoided it!

When the motor was fully warmed up this condition left me with only 8 to 10 PSI when hot, yet I never heard the lifters tick at idle!

Also with only a maximum hot pressure of 40 psi at full throttle @ 4500 rpm I found no bearing issues when I did take it apart that following spring other then what I would expect from a motor with 85K miles on it.

[78w72]

Originally Posted by markpj23

Had been flying on idiot lights thus far but now I have a gauge set for temp, volts and oil pressure. First ride today with the gauges.

Oil pressure started out around 55 psi then with the engine warmed up to 190 the oil pressure at idle would drop to 20 psi. Still 40 - 45 psi above idle.

Is this OK? I know nothing about the engine history except that it's an early 70s YT block with 6X heads. Had the valve covers off yesterday and it looks pretty clean up top anyway.

20psi at idle is fine & 40-45 warmed up is ok too if youre not reving to 5000+. rule of thumb is 10psi for every 1000 rpm. also might want to connect a mechanical oil gauge if it isnt already to confirm the electronic gauge is accurate.

what weight oil are you running? thin oil will read lower psi than a thicker oil. if youre using a 10/30 maybe try a 10/40 or even 15/40 since youre in a warm climate next oil change to see if that raises the psi a tad.

[markpj23]

Originally Posted by 78w72

20psi at idle is fine & 40-45 warmed up is ok too if youre not reving to 5000+. rule of thumb is 10psi for every 1000 rpm. also might want to connect a mechanical oil gauge if it isnt already to confirm the electronic gauge is accurate.

what weight oil are you running? thin oil will read lower psi than a thicker oil. if youre using a 10/30 maybe try a 10/40 or even 15/40 since youre in a warm climate next oil change to see if that raises the psi a tad.

Gauges are old-school mechanical type, so outside of calibration tolerances I'm reasonably sure they are accurate. I did use a 'T' fitting so the idiot light is still there to get my attention.

Have not changed the oil since I bought the car - was done just prior to purchase and has less than 200 miles on it now. Will likely go to 15/40 at the first change.

Thanks for the replies.

[78w72]

Originally Posted by markpj23

Gauges are old-school mechanical type, so outside of calibration tolerances I'm reasonably sure they are accurate. I did use a 'T' fitting so the idiot light is still there to get my attention.

Have not changed the oil since I bought the car - was done just prior to purchase and has less than 200 miles on it now. Will likely go to 15/40 at the first change.

Thanks for the replies.

just to clarify, by electric i meant gauges that use a sending unit vs an actual hard line connected to the oil gauge like a true mechanical. wasnt sure what gauges you have so just wanted to mention a mechanical gauge.

[ZeGermanHam]

Your oil pressure numbers are consistent with what my brother and I both see in our GTOs. Mine has a boring low compression 400ci, and my brother's has a hotted up 461ci.

[JLBIII]

As everyone says your pressure is good. I have a mechanical gage in mine. On a hot summer day coming off the freeway I'm reading 18psi at 775 rpm at idle using 15-40 oil.

[padgett]

Typical pre-74 Pontiac V8. In racing days the recommendation was 10 psi/1000 rpm. Remember Herb Adams saying a Pontiac engine does not need any pressure at idle so 20psi under 1,000 rpm is fine. I have been using Mobil 1 10w-30 for years.

BTW GM oil pressure sendors are notorious for failing.

[markpj23]

Thanks for all the replies