Engine: '63 GT lying about oil pressure

[subforry]

Ok, something is lying to me. I have way too much oil pressure with after market gauge.

Before I had fine oil pressure, about 10psi per 1k rpm. I did some work, and now I have practically no oil pressure on the original gauge and over 100 when rev on after market gauge.

What changed is the oil, it was bad. Now has 15w-40 with STP, because I thought I had no pressure. Filter is wix 51049. The original gauge could have been damaged when I was cleaning it. Was gummed up with sludge.

From reading posts, I checked the oil pressure relief valve. Seems ok, but not sure about the spring. I cut 1/8 inch off. Really no different.

Warmish idle is 60psi, reving will go over 100psi (seems highly unlikely it's that high). The gauge was in another car and was fine. But has been unused for many months. I may pickup another gauge tonight. BTW, the aftermarket gauge is connected at the dash where the original connects, so using stock hookup location and hose.

Any ideas? Thanks.

[StudeRich]

With heavier than 30 Wt. Oil and STP you could easily get 80 PSI or more, I think that Oil combo is a bit of overkill for a "always 70F" Hermosa Beach Day..
You definitely need a Quality Gauge.

"I did some work" is a bit vague, was there More than an Oil Change, whatever that was, could matter.
A valve adjustment, Tune Up, Valve grind, engine overhaul, engine rebuild etc.

Definitely order a New Oil Pressure Regulator Spring !
Is the regulator Piston installed correctly, pin hole down ?

But IF your original numbers were correct, a low of 10 PSI and 10 per 1000 is very Low for a full flow Stude. 289 in good condition.

[bensherb]

You can put a gauge directly in the oil gallery on the inside front of the left head. That'll give you a "second opinion" simultaneously to compare with.

My GT with 10-40 oil, when hot, will idle at 27 psi (digital gauge) just what the book says it should and will go up to 55 psi at around 3000-3500 rpm. It'll climb a bit more, maybe 60 psi at higher rpm. I don't usually run it above 5000 rpm and at that rpm/speed I'm paying more attention to driving than the gauges, so don't know exactly. BTW; It's rarely as cold as 70F here unless it's raining and I don't drive it in the rain (unless I get caught in it, it happens ). It's usually 85F or more ambient and running at around 200F coolant temp when I'm driving it.

[Bud]

If there was sludge in the oil pressure gauge, it could be the oil pressure relief valve is stuck causing the high oil pressure. When I lived in Hawthorne, Ca my 62 GT with a full flow block would hold 25 to 30 psi oil pressure at idle when hot and around 60 on the freeway with 15W-40 oil and my 63 Avanti is about the same. At any rate, I don't recommend using something like STP with 15W-40 oil. Find the cause of the problem rather than using a Band Aid like STP to mask the problem. If there was sludge in the oil pressure gauge, then there has to be a massive build up of sludge in the oil pan that needs to be cleaned out.

[Jeffry Cassel]

I've been using Valvolene 20-50 racing oil with zzdp for years. When I start the Hawks the oil pressure will be high--70psi or so. This falls to 35 45 psi as it warms up. My Case 400 tractor (1955) starts and runs at 25-30 psi and when it warms up it is still at 25-30 psi with John Deere 15-40 oil (with zzdp) I do not know why Studebaker oil pressure is varies so greatly. I do not think it can be the oil but my supply of old John Deere oil is finally running low (when they 'reformulated' I bought all the old oil the local JD dealer had and now am running low and don't really want to put it in a Hawk just to see what happens. You would think the relief valve would tend to moderate the oil pressure? (A pint of STP isn't going to increase oil pressure by very much.)

[PackardV8]

It's Studebaker-Packard heresy of the highest order to say this, but STP is garbage and should never be put in any engine!

Adding STP to 15w-40 is a VERY BAD THING! Drain it ASAP.

jack vines

[subforry]

The STP was only because I thought there was very little oil pressure. I think it's safe to assume the old gauge is bad. A second aftermarket gauge gave the same high pressure reading.

As for work. Pulled the dash and gauges. Removed the front cover to inspect the timing gears. New front seal. Removed the valve covers, adjusted the rockers. The old oil was thin, smelled of gas. Swapped intake manifolds. Engine mounts. Exhaust flange gaskets.

The oil pressure relief valve may have been stuck, but I it's free now. Small hole toward the engine. The spring seems very stiff.

Replacement oil pressure relief valve kit is one the way and an NOS gauge.

Also, I think the engine has been removed/cleaned/rebuilt? The valley was very clean, no sludge. And the expansion plugs have been replaced.

I will install the relief valve and see.

So would straight 30w be preferred?

[StudeRich]

/Cut/So would straight 30w be preferred?

Everyone will have a slightly different twist on Oil Viscosity, and LOCATION matters a lot.
Here on the West Coast, Pacific Northwest, where it never gets below +18F or over 87F and when I lived in Hawthorne and Redondo Beach until the 1990's I always used either 10W/30 winter or 20W/50 Valvoline summer, NOW we have to use Valvoline Racing VR-1 in those weights in our climate.

It is getting harder to find 30W single weight, and it does not have as wide a Temp Range as the Multi-weights do.
When I mentioned "heavier than 30W", I meant 30 or in combination.

[Buzzard]

Jack,
" It's Studebaker-Packard heresy of the highest order to say this, but STP is garbage and should never be put in any engine!

Adding STP to 15w-40 is a VERY BAD THING! Drain it ASAP."

Andy will crawl back from the grave and give you a firm talking to.
Bill

[StudeRich]

Make sure you do that Hot after running, and driving if possible, that way you will get the maximum about of Goo out as possible.

[Jeffry Cassel]

Jack: Why is STP a 'very bad thing"? I used it for decades with no adverse effects. Don't anymore because of the zzdp issue. I use zinc or Valvolene oil with zinc. (STP allegedly clings to moving parts providing some friction reduction on initial start-up.)

[PackardV8]

Jack: Why is STP a 'very bad thing"? I used it for decades with no adverse effects. Don't anymore because of the zzdp issue. I use zinc or Valvolene oil with zinc. (STP allegedly clings to moving parts providing some friction reduction on initial start-up.)

A high school friend had a forty-year career as a petroleum engineer for Chevron. He said, "You know, all those snake oil guys (STP, Marvel Mystery Oil, et al) buy their feed stocks from our refineries. If that shite were any good, if it were necesssary, we would add it to our motor oils essentially for free."

Speaking of STP and start-ups, I learned the hard lesson about STP sixty-five years ago with my first Stude; a '56 Flight Hawk. The old 185" had worn lifter bores and valve guides, thus sucked up a lot of oil. Believing everything I read, (Andy wouldn't lie to us!) I added a can of STP and thought it helped. If some is good, more is better, so I added a second can. The weather turned cold, dropped down to 25-degrees or so. Too much STP had made the oil so thick, the starter couldn't turn the engine, so I had to walk to school in the cold. I had to buy a dipstick heater to warm the oil enough to drain it out. That was the last STP for me.

jack vines

[Bud]

Jack, I agree 100%. I've disassembled engines that have been run with STP or Lucas oil additive and invariably there is a layer of that stuff in the bottom of the pan. My opinion on oil additives and that includes the ZDDP additives, is that if the additive was so great, the oil refiners would already have it in their additive package. The introduction of an additive with an unknown chemistry to the oil can upset the balance of the additive package already added to any good oil causing more harm than good. My advice is to use an oil from a reputable refiner, change it regularly and forget the additives.

[Jeffry Cassel]

STP on the bottom of the crankcase? Maybe that's why it says on the bottle to add it with the motor running? You have a point: STP and 10 below zero ain't gonna work!

[Dwight FitzSimons]

In the case of ZDDP I believe that it isn't in modern oils because it isn't allowed to be. So, one has to add a can of ZDDP to regular oil. OR, use the oil made for flat-tappet engines which already has ZDDP in it. (Or, so they say.)

BTW, anyone want to buy a case of ZDDP?

--Dwight

[JoeHall]

I have ran 20W50 oil in Studes since the 1980s, but in late 1990s switched to 15W50 Mobil 1. But it seems the modern version of Mobil 1 is not same as before. I do 10,000 mile oil changes, and before the Mobil 1 on the dipstick was still fairly clean at 5000 miles. But for several years now, Mobil 1 darkens at almost same rate as dino oil - by 5000 miles it is black. Only exception I've made to 20W50 / 15W50 in Studes is in the 56J after the last rebuild. With the Olds oil pump, in temps below around 50, the gauge runs too high, going down the road at steady 2000-2500 RPM. So I have been using 10W30 in it. Before the rebuild it was OK with 15W50, even with the Olds pump.