View Full Version : Oil Pressure and Engine Temperature

07-07-2005, 12:00 AM
Let me start off by saying I believe this is an oil viscosity issue impacting oil pump efficiency.
Monday I drove my '54 on the highway for the first time. Outside temp was about 88 degrees. For the first 15 minutes the engine temp ran in the lower third of the acceptible range, oil guage pressure indicated about 60. As the oil pressure gradually fell the engine temp rose. At the highest point pegging the needle at the far edge of the acceptible range and oil pressure reading about 25. Even climbing modest hills in the heat at 60+ mph the guage never went out of the OK range and the oil pressure never dropped (at speed) below 25.
Save for two quarts of 15-40 diesel oil I've added, the type and rating of the oil in the engine is unknown to me.
However, I believe that as the oil temp rose and the effective viscosity climbed that it lowered the efficiency of the pump. Which lead to less oil circulation and dispersion, increased friction, higher temps, etc. etc. etc.
Anyone made this same observation? I am thinking of draining the oil, replacing it with full synthetic straight 30W and adding an oil treatment for good measure. Good oil is cheaper than a new L6.
Anybody seen this sort of guage behavior ? If so did you remedy it or just move on.... [:0]


"Oh That? It's a STUDEBAKER!!"

07-07-2005, 05:30 AM
what thermostat are you running? My '55 seems to have its temp. gauge calbrated for a 160 thermostat, with a 180 thermostat it will run just at the top of the "acceptable" range.


55 Commander Starlight
62 Daytona hardtop

07-07-2005, 06:37 AM
You guys keep talking about the "acceptable" range. What exactly does that mean? I've not done the thermometer in the radiator yet, but my Stude consistently runs three tick marks off the H mark (which is about 3/4s up. It "looks" hot, but I've noticed no matter if it's 60 degrees outside or 95, it doesn't move much.

I've not pulled my thermostat to see what's in there or checked the actual temp, but it's never overheated.

Mark Anderson
1965 Studebaker Cruiser

07-07-2005, 08:12 AM
I think the oil is thinned by the rising heat.

07-07-2005, 09:44 AM
Here's a caution that was given to me by folks at Fel-Pro, the gasket making company. "If you've got an older engine. Older - in that you don't know when's the last time it was apart. Synthetic lubricants can harden "rubber" seals and gaskets and make them less effective. Some older "rubber" seals had a formulation that was/is adversely affected by synthetic oils"

Oil pressure dropping as temp goes up IS normal. Plain and simple. 25lbs of oil pressure - hot - is not a problem here. Could it possibly BE higher when hot? - Sure. Is your engine gonna self-destruct soon? - not from that oil pressure.
These Champion engines often showed some cam bearing wear after 50K miles or so. Showed it in lowered oil pressure. But they'll still go a long ways as long as you keep good oil in them on a regular basis.
You're gonna see guys bragging about their oil pressure here. It's like anything else. A nice, fresh engine will hold possibly 40 lbs hot. Too much pressure can indicate a problem too!
If you just can't stand to see that needle holding a steady 25 while you roll along, try going to 40WT or even 20-50 - and dump in a can of STP when you change the stuff. Heck, Stude promoted using STP from the get-go when they owned STP. Sure can't hurt. Might help - your nerves.;)

Miscreant at large.

1957 Transtar 1/2ton
1960 Larkvertible V8
1958 Provincial wagon
1953 Commander coupe
1957 President 2-dr
1955 President State
1951 Champion Biz cpe
1963 Daytona project FS

Mike Van Veghten
07-07-2005, 10:15 AM

First you can't get synthic oil in straight 30w.
As Biggs said, it's "normal" for the oil temp. to climb as you drive for all the reasons you stated. The water temp. should be watched. The water shouldn't be above 245 or so and the oil shouldn't be above 290 or so for any extended period of time. But you'll need direct reading gauges to see those numbers.

Castrol has worked for me in the large bearing clearance engines. It seems to hold it's viscosity at high heat better in the standard oil realm. Sorry...oil for gas engines ...is for gas engines, oil for diesel engines is for diesel engines, different requirements.

And yes, as things wear inside, the clearances will get larger and the oil pressure will drop under high heat and or high load (going up the Grapevine...).

An additive may help somewhat, just be carefull to wait a "few" seconds after pressure shows on the gage....for lube to be fully circulated before driving away.

07-07-2005, 11:58 AM
Thanks everyone.
You learn something everyday, especially about synthetic oil and older seals and gaskets. Thats not a good scenerio at all[xx(]
I think that the viscosity range is too broad in the oil I intended on using.
I'm going to drain it and run a narrower range oil that wont thin as much at higher temps than what I put in before. And I guess it will be non-synthetic.
After that I will run it out and see if that has any impact. I was so used to it running the temp guage nearly smackdab in the middle that when it headed to the far right edge of the white OK "range" on the guage and the oil pressure leveled off down in the lower part of the guage that it got me to thinking....and as my wife is fond of saying...that's a dangerous thing. :D


"Oh That? It's a STUDEBAKER!!"

07-07-2005, 01:10 PM
I have often been alarmed when looking at the temp guage in my various Studes. Two different times I've gotten one of those guages from the parts store that gives the degrees, and I install the sensor right in the water manifold(I always drill and tap the second opening in the manifold- plug it when I'm not using it), and both times the temperature was 190 to 200 on the hot days, which is fine. It's just that the temp guages Stude used are calibrated to read at 3/4 when the temperature is actually right where it should be.

And I don't know about 6 cyl. Champ engines, but I believe it's just fine for the V8 to read 20 lbs. when you sitting at an idle. If you're accelerating up through higher RPMs and it still reads 20, then you have a problem.

I wish there was a way to automatically generate an email to every new Stude owner that said 3/4 on the temp guage is OK and that 20lbs at idle is OK.

07-07-2005, 02:42 PM
FYI, my Oil Pressure guage ultimately read around 25 at approximately 60mph in 3rd gear OD.
I know that small piston aircraft engines often display this same oil pressure/engine temperature relationship. It's the perverbial which came first, the chicken or the egg scenerio. Does high engine temp lead to low oil pressure or vice versa?
I'm leaning towards the oil as the cause because in my case it's the variable I cannot nail down. I believe I know, that this car has a solid cooling system.
The good news about all this is that my 54 cruised along at 60-65 for almost an hour in 90 degree heat and the temp guage never left the safe zone in the guage markings. [8D]
Gee I love this car!


"Oh That? It's a STUDEBAKER!!"

Mike Van Veghten
07-07-2005, 02:48 PM

Did I read correctly...that you added two new quarts of oil to three quarts of old oil?

If so, old oil looses the ability to hold it rated viscosity as time goes on. I used to change the oil by this method. When the pressure went down...time for a change.

So...I'd start with a full, fresh oil change and then go on a search and destroy to deal with your problem.

Happy motoring.


07-07-2005, 03:42 PM
Only thing I could add to all the great advice Dave is, don't give up on using that great diesel oil. You can get straight SAE 30, non-synthetic diesel if you'd feel better using a single digit viscosity.

Your problem may be that you just have a bit of wear in your engine. Unfortunately our Stude engines have low oil pressure kind'a built in 'em. If the lifter bores or rockers have wear in 'em, plan on low oil pressure. There is a way to help with this, and well worth the effort, but entails plugging up a few oil supply holes.

The thing we've been led think about multi-viscosity oil is, it's supposed to get thinner when the engine is cold, to reduce "dry" starts. It's supposed to get thicker as the engine gets hotter, but in reality, I just don't see it working that well, especially if there's ANY mileage since the last change.

It "seems" to work something like that for about 1500 or so miles, especially in my diesel, that's where I can really see viscosity effect. A diesel uses higher volume, not pressure. Hell, it has a hole in the oil filter big enough to drop a normal-sized, in-line gasoline filter in it! When I use straight 30 diesel oil, it holds oil pressure longer.


07-07-2005, 08:46 PM

The "condensed version" of my previous answer is that you're angsting over something you don't need to.

I agree with Mike in that you ought to go with a fresh oil change since you don't know what sorta concoction you're running now. Diesel, gas oil, suit yourself. I'd go with single viscosity first.
Whatever you do, I seriously doubt you're gonna see a significant change at 60 hot in O/D.[:I]

Miscreant at large.

1957 Transtar 1/2ton
1960 Larkvertible V8
1958 Provincial wagon
1953 Commander coupe
1957 President 2-dr
1955 President State
1951 Champion Biz cpe
1963 Daytona project FS

07-07-2005, 09:36 PM
And switching to synthetic oil in an old engine will show you leaks you wouldn't think even a Studebaker could have.

07-07-2005, 10:47 PM
Whaddoyoumean "leaks ... even a Studebaker ..."
If you want to experience oil leaks, get a brit car. I sometimes think they were designed and built around the biggest oil leak they could find.
/ H

07-08-2005, 07:51 PM
Oil leaks are your car's method of assuring that its oil will be changed on a regular basis.

Tom Bredehoft
'53 Commander Coupe
'60 Lark VI

07-09-2005, 01:03 AM
I figured that my Champion leaked 'cause every Big Dog marks his territory...;)


"Oh That? It's a STUDEBAKER!!"

07-17-2005, 08:59 PM
I understand the Brits also drink warm beer because the fridge has Lucas wiring.;)

07-17-2005, 09:30 PM
The reason you don't see British TV's is because they couldn't figure how to make them leak oil.

07-17-2005, 09:35 PM
1. keep using the 15W40 diesel grade oil.
2. check you water temp using a candy thermometer and compare to gauge reading.
3. don't panic unless fluid are puking everywhere.
4. synthetic oil base also attacks RTV sealants, so use OEM type gasket maker or permatex type products
5. you engine and tranny should not be "lugged" or "oversped (rpms)", sometimes you just gotta go slower.
6. enjoy.

07-17-2005, 09:58 PM
Put an oil cooler on. I did this to a Kaiser. The bypass oil filter-oil went into an add on transmission cooler before draining into the pan. The Kaiser ran a mite more oil pressure.