# Oil Pressure



## 65GOATGuy (Jun 11, 2020)

Rebuilt '65 389 Tri Power, started with zinc in synthetic oil, oil pressure pegs gauge @ 60 @ 3200RPM in 4th gear, drops to 25-30 @ idle, switched to V20-50 racing oil, same pressure. Feedback on whether pressure too high? Thanks in advance for your feedback.


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## Sick467 (Oct 29, 2019)

I don't see that as being too high. I'd say acceptable to a bit low actually,bit low for the Pontiac engines I have known anyhow. I currently have two Pontiac 400's.. One has 40K miles on it and would have 70-80 psi at cold start that would settle to around 40 once warmed up. This is all at choked idle or warm idle. The other is less of a HP build and will do 60 cold and 35 warm.


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## BLK69JUDGE (Jun 10, 2010)

factory or aftermarket gauge ?
I dont like 20-50 for cold/been sitting starts but thats me
wasnt 67 the change to 80# gauge ??


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## Mine'sa66 (Oct 30, 2019)

65GOATGuy said:


> Rebuilt '65 389 Tri Power, started with zinc in synthetic oil, oil pressure pegs gauge @ 60 @ 3200RPM in 4th gear, drops to 25-30 @ idle, switched to V20-50 racing oil, same pressure. Feedback on whether pressure too high? Thanks in advance for your feedback.


Sounds about perfect to me. I'd run 10-40 with zinc


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## PontiacJim (Dec 29, 2012)

65GOATGuy said:


> Rebuilt '65 389 Tri Power, started with zinc in synthetic oil, oil pressure pegs gauge @ 60 @ 3200RPM in 4th gear, drops to 25-30 @ idle, switched to V20-50 racing oil, same pressure. Feedback on whether pressure too high? Thanks in advance for your feedback.



Factory rated oil pressure as 60 PSI @ 2,600 RPM's. Would not use 20W-50 unless your engine builder told you to because he used more bearing clearances than stock or you live in a normally hot climate. 10-40 should be all you need. You want the thinner 10W, or even 15W to reach the bearings as soon as possible - thick oil can be a little sluggish on a cold morning. With 20W-50, I would not be moving the car or revving the engine until the temp shows a little heat in the engine to ensure the oil is thinned by the heat.

New engine will also show a little higher oil pressures until things begin to seat and break in.


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## 65GOATGuy (Jun 11, 2020)

Sick467 said:


> I don't see that as being too high. I'd say acceptable to a bit low actually,bit low for the Pontiac engines I have known anyhow. I currently have two Pontiac 400's.. One has 40K miles on it and would have 70-80 psi at cold start that would settle to around 40 once warmed up. This is all at choked idle or warm idle. The other is less of a HP build and will do 60 cold and 35 warm.


Thank you, appreciate the feedback.


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## 65GOATGuy (Jun 11, 2020)

PontiacJim said:


> Factory rated oil pressure as 60 PSI @ 2,600 RPM's. Would not use 20W-50 unless your engine builder told you to because he used more bearing clearances than stock or you live in a normally hot climate. 10-40 should be all you need. You want the thinner 10W, or even 15W to reach the bearings as soon as possible - thick oil can be a little sluggish on a cold morning. With 20W-50, I would not be moving the car or revving the engine until the temp shows a little heat in the engine to ensure the oil is thinned by the heat.
> 
> New engine will also show a little higher oil pressures until things begin to seat and break in.


Thank you, very helpful.


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## 65GOATGuy (Jun 11, 2020)

Sick467 said:


> I don't see that as being too high. I'd say acceptable to a bit low actually,bit low for the Pontiac engines I have known anyhow. I currently have two Pontiac 400's.. One has 40K miles on it and would have 70-80 psi at cold start that would settle to around 40 once warmed up. This is all at choked idle or warm idle. The other is less of a HP build and will do 60 cold and 35 warm.


Thanks for your experiences.


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## PontiacJim (Dec 29, 2012)

Sick467 said:


> I don't see that as being too high. I'd say acceptable to a bit low actually,bit low for the Pontiac engines I have known anyhow. I currently have two Pontiac 400's.. One has 40K miles on it and would have 70-80 psi at cold start that would settle to around 40 once warmed up. This is all at choked idle or warm idle. The other is less of a HP build and will do 60 cold and 35 warm.



Keep in mind that Pontiac used 2 different oil pump pressures. The high performance cars got the 60 PSI pump (which I believe as introduced in 1965) and the everyday mom & pop cars got the 40 PSI pump which is why the differences in oil pressures above.


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## GtoFM (Mar 23, 2018)

If you have another gauge, connect it to confirm readings. Most gauges and meters are more accurate at mid-scale, so I prefer a 0-80 psig with a 270* sweep.


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## Old Man Taylor (May 9, 2011)

I also use 10-40. My idle oil pressure when warm is below 20 psi, and it is not a problem


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## O52 (Jan 27, 2019)

OMT Check your messages


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