Engine: Oil Pressure too low or ????

[Dan White]

I got the idle set on the '57 Broadmoor Wagon (Marvin as my son calls it now). I put a gauge on the front oil galley plug. At start up it registers 45 lbs or so. After full warm up it is reading about 5 - 6 lbs at idle. I believe my Hawk's gauge reads about 10 to 15 (full flow block) at idle. Also the light is not coming any longer on so it appears that the sensor is OK. So is 5 - 6 lbs. OK at idle? I just put in some generic 10W30 until I get the rear main fixed. I thought about putting in a can of STP to see what that does. Engine only has about 56K miles.

[SN-60]

To: Dan White,---- For one thing, I'd run a straight weight oil in that car in warmer weather. Probably straight 30W. And adding a pint of STP wouldn't hurt.

[rodnutrandy]

Not at all a Studebaker engine specialist, but 5 Lbs. sounds low to me. On my 350 SBC (sorry) , I had low oil pressure after warm up. I believe it was due to motor being built by a race engine builder and has a little more clearance, I went from a 10w30 to 20w50 and now have good pressure at all times. That worked for me. ps I don't run truck in winter so 20w50 doesn't pose a question.

[Bud]

I would say to try a 15W-40 oil such as Shell Rotella T or Chevron Delo 400. I've been using the Delo 400 in my Studebaker engines for last 30 years with great results. 5 lbs oil pressure at idle is a bit low but not the end of the world. I would recommend cleaning the oil pressure relief valve if that hasn't been done lately as it may be stuck or sticking as a sticking relief valve can cause low oil pressure at idle. Bud

[tbredehoft]

There have been a large number of concerns about low oil pressure at idle lately. Studebaker was only concerned about pressure at 40 mph in road gear, should be 40 psi. Since you don't drive the car when its idling, and since there is no load on it then, there is no need for anything but moving oil. Don't worry about low pressure at idle, they didn't when they made the cars.

[raprice]

I use 20W-50 oil in my '59 Lark VI due to lower oil pressure. It's interesting that, when I start the car up from cold, the oil pressure reads up to 60 psi. After the engine warms up, the gauge reads 30 psi and around 20 psi at idle. I haven't had any problems with it. I do add ZDDP to the oil when I change it in the Fall.
I switched to 20W-50 after reading a letter to "The Cooperator" in TW, some time ago, from someone who had a similar concern to mine. It seems to have worked.
Rog

[Dan White]

I normally use Rotella or Delo 15W-40 but just did not on this one since I was losing a lot of oil with the rear main. We will see what happens after I get the rear main fixed, clear the oil pickup strainer.

[Dan White]

Took the car on a drive. The oil pressure drops to about zero when I stop before it down shifts. When running it only gets to about 15 to 20 lbs. So either the pickup screen is clogged or the bearings are shot. Hope it is the pickup! I will take it over to a friend who has a lift and drop the pan and see what it looks like.

[SN-60]

To: Dan White,----Sorry, but it sounds like a really tired 55 year old engine to Me.

[PackardV8]

Yes, 5 PSI at idle is plenty.

No, 20 PSI at cruise isn't enough. There's a bunch of loose leaks somewhere, or as you hope, a partially clogged pickup screen.

Maybe, change the oil and filter one more time. There's always a lot of crud to be cleaned out of any old engine which has been sitting a while. Make sure the pressure relief valve is moving freely. Also double check the restrictor fitting is present in the oil filter line.

jack vines

[radiotech]

Hey Dan, check the pressure line going to the oil filter, one of the fittings should have a restriction in it. Hole should be about .045" as I recall! Found this out the hard way on my 40 Commander years ago, had the same exact problem you are and that was with a rebuilt engine.

[jasontaub9]

Excessive main bearing clearance can also cause low oil pressure.