1940 Buick Super Oil Pressure question

[Kurtfreudenberg]

The car runs great but I noticed the oil pressure drops from 45 lbs to 5 to 10 when the car is warmed up. It has no knocks or taps. Is this drop in pressure normal?anything I need to do?

Appreciate any comments

[Grant Magrath]

About right at idle when warm. It should come up as your speed increases. If it still worries you, go to a heavier oil. There are some good threads here on the forum that discuss various properties of oil required for our old cars.
Cheers
Grant

[shadetree77]

The straight eight in my '52 does the same thing. From what I've read on other posts, it is pretty normal for the pressure to drop off like that at an idle. Like Grant said though, it should increase again as you increase your speed. If it stays that low cruising down the road, you may well have a problem.

[Tom_S]

How do you search for the threads about oil properties for the old cars?
Thanks,
Tom

[The Old Guy]

My 40 has shown 5-8 pounds at hot idle since I put the engine in. It hasn;t changed in 30+ years and 100,000+ miles

[Kurtfreudenberg]

Thanks for the comments guys

[FLYER15015]

Kurt,
Is this a "new" car to you ?
Have you pulled the pan and cleaned out the usual 1-2" of mud from the bottom?
When you do, take time to pull the oil pump (it's just 2 bolts) and check the clearance of the 2 gears to the bottom plate.
I used "plasti gage" (for checking bearings). You should have about 2 thousandths of an inch, and you can accomplish this by polishing the housing on a good flat surface w/ some 60+120 grit emery cloth. Mine measured .004", and my gage was like yours. I also stretched the pressure relief spring from 2.75" to 3.25" An old trick a mechanic taught me many years ago.
Mike in Colorado

[Kurtfreudenberg]

Kurt,
Is this a "new" car to you ?
Have you pulled the pan and cleaned out the usual 1-2" of mud from the bottom?
When you do, take time to pull the oil pump (it's just 2 bolts) and check the clearance of the 2 gears to the bottom plate.
I used "plasti gage" (for checking bearings). You should have about 2 thousandths of an inch, and you can accomplish this by polishing the housing on a good flat surface w/ some 60+120 grit emery cloth. Mine measured .004", and my gage was like yours. I also stretched the pressure relief spring from 2.75" to 3.25" An old trick a mechanic taught me many years ago.
Mike in Colorado

Thanks for the advise. I have cleaned the pan but will check out the other tips. Thanks again!

Kurt in NY