# Is my oil pressure too low?



## Donjun (6 mo ago)

Hi all. I am new to the forum. I just picked up a 68 GTO 400 a couple weeks ago. I am concerned with the oil pressure. My gauge reads 12 after cruising at 55 mph then coming to a stop and still in drive. The engine is fully heated up. I checked with a second gauge and get the same reading. Should I be concerned? Thanks for any comments.


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## Donjun (6 mo ago)

Also I just changed the oil and filter with 10W-40.


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## Sick467 (Oct 29, 2019)

Welcome to the forums! 12 psi is really low. I would be concerned. That tells me, in general, that your engine is fairly worn and/or your oil pump is failing. If you do not have any other signs like ticking or knocking, that 12 psi is doing it's job, but I would keep a very close eye on it and never drive it like you want too....meaning do not hot rod it. Drive it like you have an egg under the go-peddle!

If it were me, I'd plan on a rebuild since I would not be able to keep my foot out of it. AND, much worse damage can happen to otherwise salvageable parts, like the crank and block, should you lose oil pressure all of a sudden and not get pulled over before the damage is done.

Some will suggest using a thicker oil, but IMO a thicker oil improves your gage reading, but not much else. Maybe it can lengthen the life of the motor with what you have going on by adding the thickness of the oil to the worn bearing clearances...I would not risk it with an old Pontiac, maybe an old beat up Cheby...lol!


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## Ebartone (Aug 18, 2019)

Donjun said:


> Hi all. I am new to the forum. I just picked up a 68 GTO 400 a couple weeks ago. I am concerned with the oil pressure. My gauge reads 12 after cruising at 55 mph then coming to a stop and still in drive. The engine is fully heated up. I checked with a second gauge and get the same reading. Should I be concerned? Thanks for any comments.


Welcome! So tell us a bit more about this engine. Is it just rebuilt, or many miles? Stock or decked out with large clearances? What is the cold idle pressure, and cold cruise pressure? What is the hot cruise pressure?


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## Bopman (7 mo ago)

Donjun said:


> Hi all. I am new to the forum. I just picked up a 68 GTO 400 a couple weeks ago. I am concerned with the oil pressure. My gauge reads 12 after cruising at 55 mph then coming to a stop and still in drive. The engine is fully heated up. I checked with a second gauge and get the same reading. Should I be concerned? Thanks for any comments.


What is the pressure while at 55 mph ?


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## Mine'sa66 (Oct 30, 2019)

Donjun said:


> Also I just changed the oil and filter with 10W-40.


What was it before you changed the oil/filter?
As others have asked, what is it at cruise? What is it cold at idle?
What RPM does it idle at when warm?
You may or may not have an issue depending on some of the other info


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## Jared (Apr 19, 2013)

Where are you pulling the oil pressure reading from? Oil filter housing or back of the block near the distributer? 12psi at the filter is not good, at the distributer is even worse. I'm in the time for a rebuild camp too. The engine not making noise yet is not a sign that you don't have a failure in the future. The engine that came out of mine wasn't making any noise either until the crank shaft broke into 5 pieces. Only sign that anything was wrong was low oil pressure and a rattle in the shifter inside the car.


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## Donjun (6 mo ago)

Sick467 said:


> Welcome to the forums! 12 psi is really low. I would be concerned. That tells me, in general, that your engine is fairly worn and/or your oil pump is failing. If you do not have any other signs like ticking or knocking, that 12 psi is doing it's job, but I would keep a very close eye on it and never drive it like you want too....meaning do not hot rod it. Drive it like you have an egg under the go-peddle!
> 
> If it were me, I'd plan on a rebuild since I would not be able to keep my foot out of it. AND, much worse damage can happen to otherwise salvageable parts, like the crank and block, should you lose oil pressure all of a sudden and not get pulled over before the damage is done.
> 
> Some will suggest using a thicker oil, but IMO a thicker oil improves your gage reading, but not much else. Maybe it can lengthen the life of the motor with what you have going on by adding the thickness of the oil to the worn bearing clearances...I would not risk it with an old Pontiac, maybe an old beat up Cheby...lol!


Thanks


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## Donjun (6 mo ago)

Ebartone said:


> Welcome! So tell us a bit more about this engine. Is it just rebuilt, or many miles? Stock or decked out with large clearances? What is the cold idle pressure, and cold cruise pressure? What is the hot cruise pressure?


It is a stock engine, not rebuilt. It has 101,017 miles. The cold idle is 52. The cold cruise is 60 at 40mph. The hot cruise at 60mph is 48. The hot cruise at 50mph is 42. The hot cruise at 40mph is 31. The hot cruise at 30mph is 25.


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## Donjun (6 mo ago)

Bopman said:


> What is the pressure while at 55 mph ?


45


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## Donjun (6 mo ago)

Mine'sa66 said:


> What was it before you changed the oil/filter?
> As others have asked, what is it at cruise? What is it cold at idle?
> What RPM does it idle at when warm?
> You may or may not have an issue depending on some of the other info


See my answer to Ebertone. The pressure did not change after changing the oil.


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## Donjun (6 mo ago)

Jared said:


> Where are you pulling the oil pressure reading from? Oil filter housing or back of the block near the distributer? 12psi at the filter is not good, at the distributer is even worse. I'm in the time for a rebuild camp too. The engine not making noise yet is not a sign that you don't have a failure in the future. The engine that came out of mine wasn't making any noise either until the crank shaft broke into 5 pieces. Only sign that anything was wrong was low oil pressure and a rattle in the shifter inside the car.


The reading is by the oil filter.


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## Ebartone (Aug 18, 2019)

Donjun said:


> It is a stock engine, not rebuilt. It has 101,017 miles. The cold idle is 52. The cold cruise is 60 at 40mph. The hot cruise at 60mph is 48. The hot cruise at 50mph is 42. The hot cruise at 40mph is 31. The hot cruise at 30mph is 25.


We’ll, thanks for that, it’s helpful. Unfortunate that when warm even at higher rpm you are having problems making pressure. For stock at those rpm you should be holding near 60, especially with the 40 weight. Granted as you slow down a drop is expected, but your problem seems consistent through the rpm range. Combined with the age of the engine, yes, I’d be a bit concerned. The good news is that it’s still together, so a rebuild is a lot less expensive then if it comes apart. My opinion would be to consider yourself lucky it has so many miles and is rebuildable, and make a project out of it before something bad happens.


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## Jared (Apr 19, 2013)

Try plumbing it to the plug near the distributer and see what it looks like. This may not be catastrophic yet but it sounds like you have a tired engine on your hands. I'd still start setting a little aside and figure a rebuild is in the not so distant future. A stock rebuild probably won't be too pricey if you catch it before it blows. I'd budget for a new crank and rods since it is not uncommon to find cracks in the 50+ year old originals.


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## Bopman (7 mo ago)

Donjun said:


> 45


Most likely as others have said rebuild in your future. Most likely bearing are worn. I have always been told cam bearings are the main ones to cause pressure drop. But I believe pump and all bearings lead to low pressure. Just my opinion though !


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## Jim K (Nov 17, 2020)

I'm with everyone else here.. Looks like it is time for a rebuild. Bottom line, even if it is a worn out oil pump, you're still going to have to open up the motor. Might as well pull it and dive into it.


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## PontiacJim (Dec 29, 2012)

Donjun said:


> It is a stock engine, not rebuilt. It has 101,017 miles. The cold idle is 52. The cold cruise is 60 at 40mph. The hot cruise at 60mph is 48. The hot cruise at 50mph is 42. The hot cruise at 40mph is 31. The hot cruise at 30mph is 25.


Pontiac rated their oil pumps as 60PSI over 2,600 RPM's, so your RPM's will also be a factor. So if you have a set of 3.08 rear gears, 26" tall tires, you would need to be at 65 MPH to have your RPM's at/near 2,600 RPM. As Speeds/RPM's go down, so will oil pressure. How hot the engine runs will also affect oil pressure.

What is the engine idle RPM at 12 PSI? Too low of an engine idle can show up as low oil pressure.

But, if still original and never rebuilt, 101,017 miles is most likely worn out for a GTO that still has its original engine. You could do a cylinde pressure check to see what the PSI is in each cylinder which will give you the condition of your rings and may show how worn the engine is. I have to assume that the factory timing chain and gears have been changed out as the nylon teeth on the aluminum cam gear usually are toast by around 60K miles and the chains also stretch.

Along with others, you might want to consider a rebuild at this point as the engine is most likely worn out and your bearing clearances are larger due to the wear which drops oil pressure. Oil pump could be worn out, but you have to pull the engine to replace it IF the rest of the internals were in good shape.

Oil filters can also make a difference, some do not flow as well as others and can become a restriction and cause a lowered oil pressure. The Wix/Napa Gold brand is a good flowing oil filter.


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## ponchonlefty (8 mo ago)

i have seen the nylon gear break and jump timing. the pieces get into the oil pump pick up. and people would just change the timing chain and gears. and have low oil pressure like that. the only fix would be pull the pan change the oil pump. most likely a full rebuild is in order.


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## Donjun (6 mo ago)

Thank you to all of the replies and advice. I suspected a rebuild was in order. Now I will get it done. Will post in the future with the results.


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## Mine'sa66 (Oct 30, 2019)

I'm more not with everybody else.
I think you stated that you're getting no symptoms. No bad noises etc.
I'll quote a learned technician that was an oldtimer when I started turning wrenches in the early 1980's
When it comes to oil pressure, any is enough.
Now, that's obviously an over simplification, and just enough isn't "good" but as long as oil is circulating and at enough pressure to keep hydro lifters pumped up, then you're winning.
You never did state what RPM it idles at warmed up? At real low RPM, just another 50-75 RPM can change that oil pressure by a handful of PSI. Change your question from "it's 12psi at warm idle" to "it's 18 psi at warm idle" and it's a very different feeling.
I don't suggest a whole lot of top end 1/4 mile passes with it, but, I'd wager with the oil pressure numbers you're seeing across the board that that engine will soldier on for a substantial amount of time.
I'd watch it, watch for changes, listen for noise. As mentioned, filters do make a difference. You stated it didn't change after the LOF, but did you replace the filter with another of the same? Just for chucks, you might try a different one. Wix are fine, I might search down an AC/Delco filter. You're not looking for a filter that has huge "flow", you're looking for one that mimics the resistance the OE one had.


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## lust4speed (Jul 5, 2019)

Guess I'm on the other side of this. Pontiac oil pressure warning light senders turn on the light below 4.5 to 5 pounds of pressure so Pontiac wasn't exactly worried about mediocre oil pressure at idle. I know of a couple of engines in our GTO club that idle about 10 PSI and they continue to run without mishap. Another engine was really frustrating in that the friend had it rebuilt and pressures remained very low after the rebuild. He took it to another shop and they set clearances on the tight side, but the engine still only had about 8 PSI at hot idle and worse it only had 38 PSI at 5,000 RPM. At that point he said the hell with it and ran it like he stole it, and to this day the engine is still doing fine years later. In this particular case we figure that there had to be a casting flaw somewhere in the oil gallery bleeding off pressure.

An interesting tidbit is that the slanted filter adapter used for the A-bodies have the pressure fitting in the adapter before the filter so a restrictive filter would actually raise the observed pressure. The big car adapters had the pressure fitting after the filter. Sort of a moot point on filter restriction since the relief spring inside the adapter releases at about 2-1/2 pounds of pressure difference if the filter is clogged.

Might not hurt to mention that only the H.O. and RamAir engines came with a 60 PSI spring in the oil pump. My '67 service manual calls for 35 PSI above 2,600 RPM for standard engines and 60 PSI above 2,600 RPM for H.O. and RamAir engines. Those 60 PSI pumps received a cadmium plated distributor gear for the extra stress. Today about every Melling pump comes with a 60 PSI spring and they don't worry about the gear.

Also take into account that your gauge could be reading lower than actual pressure.

Drive and enjoy your new purchase, and as with any old stock engine it should not be abused.


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## ponchonlefty (8 mo ago)

lust4speed said:


> Guess I'm on the other side of this. Pontiac oil pressure warning light senders turn on the light below 4.5 to 5 pounds of pressure so Pontiac wasn't exactly worried about mediocre oil pressure at idle. I know of a couple of engines in our GTO club that idle about 10 PSI and they continue to run without mishap. Another engine was really frustrating in that the friend had it rebuilt and pressures remained very low after the rebuild. He took it to another shop and they set clearances on the tight side, but the engine still only had about 8 PSI at hot idle and worse it only had 38 PSI at 5,000 RPM. At that point he said the hell with it and ran it like he stole it, and to this day the engine is still doing fine years later. In this particular case we figure that there had to be a casting flaw somewhere in the oil gallery bleeding off pressure.
> 
> An interesting tidbit is that the slanted filter adapter used for the A-bodies have the pressure fitting in the adapter before the filter so a restrictive filter would actually raise the observed pressure. The big car adapters had the pressure fitting after the filter. Sort of a moot point on filter restriction since the relief spring inside the adapter releases at about 2-1/2 pounds of pressure difference if the filter is clogged.
> 
> ...


 if its numbers matching i would not risk it.


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## RMTZ67 (Mar 12, 2011)

Mine'sa66 said:


> I'm more not with everybody else.
> I think you stated that you're getting no symptoms. No bad noises etc.
> I'll quote a learned technician that was an oldtimer when I started turning wrenches in the early 1980's
> When it comes to oil pressure, any is enough.
> ...


And what is his idle set at?


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## AZTempest (Jun 11, 2019)

Mine'sa66 said:


> I'm more not with everybody else.
> I think you stated that you're getting no symptoms. No bad noises etc.
> I'll quote a learned technician that was an oldtimer when I started turning wrenches in the early 1980's
> When it comes to oil pressure, any is enough.
> ...


I tend to agree with this side of the coin. No symptoms, car runs fine, drive it. 

One thing not mentioned is the climate being driven in. If your in an extreme temperature area that could effect your decisions for oil as well. Here in the Phoenix area I run 20w-50. In the summertime I tend to not drive my cars at all mainly cause it's not fun putting up with 110F everyday. (Sometimes I'll pull one out in the evening and put up with 99F.... lol.) It will not hurt to try a slightly heavier viscosity and see what psi you get. Also I don't recommend synthtic for an older engine. Stick with conventional. Sure you're close to a rebuild, but it's a normal engine that's worn. Keep the oil clean and the car tuned and run it.


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## PontiacJim (Dec 29, 2012)

lust4speed said:


> Guess I'm on the other side of this. Pontiac oil pressure warning light senders turn on the light below 4.5 to 5 pounds of pressure so Pontiac wasn't exactly worried about mediocre oil pressure at idle. I know of a couple of engines in our GTO club that idle about 10 PSI and they continue to run without mishap. Another engine was really frustrating in that the friend had it rebuilt and pressures remained very low after the rebuild. He took it to another shop and they set clearances on the tight side, but the engine still only had about 8 PSI at hot idle and worse it only had 38 PSI at 5,000 RPM. At that point he said the hell with it and ran it like he stole it, and to this day the engine is still doing fine years later. In this particular case we figure that there had to be a casting flaw somewhere in the oil gallery bleeding off pressure.
> 
> An interesting tidbit is that the slanted filter adapter used for the A-bodies have the pressure fitting in the adapter before the filter so a restrictive filter would actually raise the observed pressure. The big car adapters had the pressure fitting after the filter. Sort of a moot point on filter restriction since the relief spring inside the adapter releases at about 2-1/2 pounds of pressure difference if the filter is clogged.
> 
> ...



The GTO got the higher 55-60 PSI oil pressure pumps. The Pontiac full size got the lower 30-40PSI oil pumps.


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## Donjun (6 mo ago)

lust4speed said:


> Guess I'm on the other side of this. Pontiac oil pressure warning light senders turn on the light below 4.5 to 5 pounds of pressure so Pontiac wasn't exactly worried about mediocre oil pressure at idle. I know of a couple of engines in our GTO club that idle about 10 PSI and they continue to run without mishap. Another engine was really frustrating in that the friend had it rebuilt and pressures remained very low after the rebuild. He took it to another shop and they set clearances on the tight side, but the engine still only had about 8 PSI at hot idle and worse it only had 38 PSI at 5,000 RPM. At that point he said the hell with it and ran it like he stole it, and to this day the engine is still doing fine years later. In this particular case we figure that there had to be a casting flaw somewhere in the oil gallery bleeding off pressure.
> 
> An interesting tidbit is that the slanted filter adapter used for the A-bodies have the pressure fitting in the adapter before the filter so a restrictive filter would actually raise the observed pressure. The big car adapters had the pressure fitting after the filter. Sort of a moot point on filter restriction since the relief spring inside the adapter releases at about 2-1/2 pounds of pressure difference if the filter is clogged.
> 
> ...


I have the 68 service manual. I've looked and looked but I cannot find anything about PSI.


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## Donjun (6 mo ago)

PontiacJim said:


> The GTO got the higher 55-60 PSI oil pressure pumps. The Pontiac full size got the lower 30-40PSI oil pumps.
> 
> View attachment 156472
> View attachment 156473


Where did you find these specs? I have a 68.


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## PontiacJim (Dec 29, 2012)

Donjun said:


> I have the 68 service manual. I've looked and looked but I cannot find anything about PSI.


1968 Service Manual, Page 295, Section 6-79 of the engine specs.


The SM lists oil pressure for the GTO as 45-50 PSI @ 2,600 RPM's. This is the same as the 1965-66 389 specs and AMA Specs. Seems 1967 AMA specs were changed on the 400CI to the 55-60 PSI for the GTO. So this may be a carry-over number from the earlier 1965-66 specs as not all changes are made in the Service Manual and you can find info/photos from older years that still apply.

I looked at the AMA for 1966 GTO - the same 45-50 PSI. Then from 1967 on with the 400CI, in the AMA Specs, 55-60 PSI for '68, '69 GTO and the Optional 350HO in the Lemans, BUT NOTE in 1969 what shows up in the AMA Specs is 30-40 @ 2,600 PSI in the GTO's Optional Regular Fuel Engine (2 bbl low compression) which was also available beginning 1967 and believe is what is listed in the Service Manual as the "Standard" right above GTO & 428.

That said, it would now appear the lust4speed's manual is for the "Standard" engine, just like the 1968 Manual, which must be the 2 Bbl, regular fuel, low compression, economy engine option available on the GTO based on the note found in the 1969 AMA Spec Sheet.

Now it could be argued that the "Standard" engine for the 1967 GTO was the 335HP @ 5,000 RPM's, for 1968 350HP @ 5,000 RPM, and 1969 350HP @ 5,000 RPM.

So a little more investigation -

The 2Bbl engine for 1967 was 255HP @ 4,400 RPM, for 1968 was 265HP @ 4,600 RPM, for 1969 was 265HP @4,600 RPM.

I then looked at the B-Body full size cars. The only engine that used the 55-60 PSI oil pump were those having an RPM of 5,100 (428HO - 1967) and 5,200 (428HO - 1968/69). All other B-body engines maxed out at 4,800 RPM and used the 30-40 PSI oil pump.

What I see is that any Pontiac engine that spun 5,000 RPM's or more got the 60 PSI oil pump beginning in 1967. The other engines got the lower 30-40 PSI oil pumps and the reference to "Standard" engine in the Service Manual is referencing the Optional 2Bb Regular Fuel Low Compression engine based on what the 1969 AMA Specs noted.

So, you can see how the Service Manual and AMA Spec Sheet are not always 100%, nor explain all things in detail, and they do change or are amended as production changes are made.

AMA Spec Sheet - some were purchased from Ebay and a couple were gotten online.

That's my story on the factory oil pump pressures and I am sticking to it.  

Rule of thumb has always been 10 PSI for every 1,000 RPM's. The engine does wear and bearing clearances and other part get wider allowing more oil to leak out, so oil pressure will naturally drop over time. No one can be 100% correct as to run the engine as is because the oil pressures look ok, or rebuild the engine because the oil pressure looks low. Most of my cars had idiot lights and we were never concerned about oil pressure - just keeping oil in it because they used a lot of oil. So it is your engine and your call. You can keep running it and it may never give you issue or keep running it and the oil pressure goes away tomorrow. No one can predict that. But what you don't want to do is be in fear every time you take the car on a drive and all you do is keep looking at the oil pressure gauge to make sure "things" are OK and don't enjoy the car. At this point, you know what the oil pressure is, you may or may not have an issue - THROW THE OIL GAUGE AWAY and just drive the car until IT lets you know the engine needs a rebuild - IF that time ever comes. If you simply want to rebuild the engine, then do so.


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## BearGFR (Aug 25, 2008)

The "rule of thumb" for reasonably safe oil pressure in a street engine, is 10 psi per 1000 RPM. If you've got at least that, you should not be in immediate danger. While your pressure may be a little on the low side and indicating that it might be time to start thinking about freshening the engine, I don't think it's "OH MY GOODNESS IT'S GOING TO BLOW ANY SECOND!" low. 

My 0.02 - void where prohibited by law, past performance is not a guarantee of future return, slippery when wet.

Bear


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## Donjun (6 mo ago)

PontiacJim said:


> 1968 Service Manual, Page 295, Section 6-79 of the engine specs.
> 
> 
> The SM lists oil pressure for the GTO as 45-50 PSI @ 2,600 RPM's. This is the same as the 1965-66 389 specs and AMA Specs. Seems 1967 AMA specs were changed on the 400CI to the 55-60 PSI for the GTO. So this may be a carry-over number from the earlier 1965-66 specs as not all changes are made in the Service Manual and you can find info/photos from older years that still apply.
> ...


Thanks


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## geeteeohguy (Feb 2, 2008)

IMO, the OP doesn't have an issue. He has high mileage on an original engine and enough oil pressure to get the job done and not risk parts failure. I would be much more worried if it had the stock timing chain and nylon cam gear. I would run 15/40 diesel spec oil and a Wix filter and call it good to go. FWIW, I am also an 'old timer' who has been turning wrenches since the late '70's.


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## O52 (Jan 27, 2019)

Nice thing about indicator lights vs gauges. 
No worries.
Oil pressure light clicks on at 5-7 PSI.
Coolant temperature light at 245º. Pontiac even states that no engine damage will occur up to 265º


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## geeteeohguy (Feb 2, 2008)

O52 said:


> Nice thing about indicator lights vs gauges.
> No worries.
> Oil pressure light clicks on at 5-7 PSI.
> Coolant temperature light at 245º. Pontiac even states that no engine damage will occur up to 265º


Truer words were never spoken. I always worry when I'm driving the cars with full gauges, and never worry when I'm driving my idiot-light '67. And haven't for the past 39 years. Probably why I've taken it everywhere....ignorance can be bliss, I guess!!


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## gtojoe68 (Jan 4, 2019)

My two cents here - rebuild is likely in order, yes. And Pontiacs are NOT the same as SBC for cost. I did a fairly basic rebuild on my original motor and paid $4k. Also - my old shop teacher in early 80's always swore by 10lbs per 1000 RPM for a minimum oil pressure.


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## Baaad65 (Aug 29, 2019)

Agreed, as long as it's there when it counts.


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## flatbill (Oct 5, 2020)

If money is tight now pull the pan, clean it out, replace the main and rod bearings with new standard size and maybe a new pump and pickup. Do it in the chassis for a nice project. Enjoy for a good long while. Billk


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## PontiacJim (Dec 29, 2012)

flatbill said:


> If money is tight now pull the pan, clean it out, replace the main and rod bearings with new standard size and maybe a new pump and pickup. Do it in the chassis for a nice project. Enjoy for a good long while. Billk


You cannot do it in the chassis. The engine has to be pulled. Have done that on a Chevy truck, but you cannot do it with a Pontiac - you can't get the pan off.


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## Herding Goats (Sep 16, 2017)

Good question @RMTZ67. As PJ and more have posted in other oil pressure threads, idle speed matters when judging idle oil pressure. I don't have my shop manual or the '68 with emission decal in front of me, but am guessing idle should be somewhere around 650 rpm for automatic (in gear) and 850 rpm for manual (in neutral). 30% more RPM will raise the oil pressure a lot at low speeds. I have seen 650 to 850 add at least 10 psi. Makes sense why Pontiac specced oil pressure at a specific RPM.


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## JohnStauver (Nov 29, 2020)

Donjun said:


> Hi all. I am new to the forum. I just picked up a 68 GTO 400 a couple weeks ago. I am concerned with the oil pressure. My gauge reads 12 after cruising at 55 mph then coming to a stop and still in drive. The engine is fully heated up. I checked with a second gauge and get the same reading. Should I be concerned? Thanks for any comments.


From an old old engine builder. No other symptoms or noise indicates worn cam bearings. A complete build may cover every base but be unnecessary. Amen to the recommendation of an AC Delco oil filter too.


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## Scott06 (May 6, 2020)

Mine'sa66 said:


> I'm more not with everybody else.
> I think you stated that you're getting no symptoms. No bad noises etc.
> I'll quote a learned technician that was an oldtimer when I started turning wrenches in the early 1980's
> When it comes to oil pressure, any is enough.
> ...


 I'm with you, I think OP is more ok than not. I have always used 10 psi/1000 rpm (hot) as a rule of thumb. Only bearing related engine failures I had were below this. Certainly and original engine at 100 k has wear but if you have a legit 12 psi at idle and 42-48 psi hot at highway speeds I think you are ok if engine is not making ticks or knocks.

As an example I repowered my boat a few years back with a new GM marine crate engine. Hot idle is 15 psi on 40 wt ... 55-60 psi at WOT 5 k rpm. 

As others have suggested try 50 w if you are worried.


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## geeteeohguy (Feb 2, 2008)

PontiacJim said:


> You cannot do it in the chassis. The engine has to be pulled. Have done that on a Chevy truck, but you cannot do it with a Pontiac - you can't get the pan off.


You can indeed do it in the chassis. I even have the special tool that holds the front of the engine waaaaay up off the crossmember. My old boss who worked at Pontiac in 1970 gave it to me. It's a huge plate that bolts up where the timing cover would be with a jack foot on it. Very clumsy to use and not really safe. 
That said, it takes about twice as long and it's much messier and less accurate job trying to do it in-car because the oil pump pickup is very long. 
It's much easier to pull the engine, flip it over, and do the job right. I would never, every do one 'in car' again. 
Pulling the engine and rolling in new bearings and re-sealing it can be done in a day by a pro or a weekend by an amateur. 
If it were me, I'd simply install the 15/40 and run it as is until rebuild time. If I were going to pull the engine, I'd to a rebuild. 
Depending on your skill level, it can remain affordable....under 2k if you do the dis-assembly and re-assembly.


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## PontiacJim (Dec 29, 2012)

geeteeohguy said:


> You can indeed do it in the chassis. I even have the special tool that holds the front of the engine waaaaay up off the crossmember. My old boss who worked at Pontiac in 1970 gave it to me. It's a huge plate that bolts up where the timing cover would be with a jack foot on it. Very clumsy to use and not really safe.
> That said, it takes about twice as long and it's much messier and less accurate job trying to do it in-car because the oil pump pickup is very long.
> It's much easier to pull the engine, flip it over, and do the job right. I would never, every do one 'in car' again.
> Pulling the engine and rolling in new bearings and re-sealing it can be done in a day by a pro or a weekend by an amateur.
> ...



You want me to quote from the 1968 Service Manual and my personal experience????

1968 SM:

"OIL PAN AN/OR OIL PAN GASKET- REMOVE AND REPLACE - TEMPEST MODELS.

1. *Remove engine*, and clutch (SM-syncromesh) from vehicle.
2. Place engine on a suitable stand.
3. Remove oil pan."

Pretty clear to me. Maybe the Pontiac engineers got it wrong.

In doing the oil pump on my '68 Lemans, I did this by dropping the pan down, not out - the pan WILL NOT clear the crossmember as it hits the crank because the engine cannot be lifted high enough before the bell hits the trans tunnel- you may also have an issue with the exhaust hitting the floor. You can drop the pan down just enough to slip your hand in through the small gap between the pan rail and engine. You cannot use 2 hands, so just decide which arm/hand you will be using and possibly lose. Make sure the engine is very secure because if it falls or shifts while your hand and wrist are inside, you will be pinned and probably do some serious damage to the arm structure. BUT, once you can get your hand in, you have to work blind and "feel" your way to get your ratchet/socket on the oil pump bolts. You can peak in using a light for some help. Break them loose and remove the pump. If the oil pump driveshaft slides out, which is most likely, be prepared to have fun sliding it back into the shaft's hole and locking the tang end into the distributor gear and keeping it in place as its weight wants to drop it back out while trying to juggle the new oil pump back in and on. With the pan down, use a razor blade to thoroughly clean the oil pan and engine rail. The gasket shavings that fall into the drained pan can be mopped up and removed using a rag that can be blindly moved about the bottom of the pan until it comes back out clean. Re-insert the oil pump shaft if it has fallen out - I used wheel bearing grease to hold it up into its hole and turned the shaft to lock into the distrib. gear. Then snake the new pump and pickup with gasket tacked on into the pan and onto the oil pump face on the block - BUT, have a bolt in palm so that once in place you can wriggle the bolt out of your palm while holding the pump up and insert it into the pump/block and finger tighten. Once in the second bolt goes much easier. Tighten with ratchet/socket. Then use the torque wrench with corresponding attachments so the torque wrench will stick out the pan and you can apply the torque. When done, install a new gasket and close up the pan. Drop engine back down on the mounts, bolt everything back up, install the distributor cap, add oil, and fire it up.

Now lets see what the '68 SM says for the full size Pontiacs:

"OIL PAN AN/OR OIL PAN GASKET- REMOVE AND REPLACE - PONTIAC MODELS

1 - 6 is disconnect everything.
7. Raise vehicle and drain crankcase.
8. Disconnect steering idler arm from frame.
9. Remove exhaust crossover pipe. When equipped with dual exhaust disconnect pipes from manifolds.
10. Remove starter assembly and flywheel cover.
11. Position J 22603 ENGINE LIFTING TOOL to engine and place J 22603-4 CROSS BAR in position on lifting tool. Bolt tool to timing chain cover with bolts provided with tool.
12. Using frame jacks or hydraulic transmission jack, support engine at J 22603, remove motor mounts.
13. Loosen (or remove) rear transmission mount.
14. Remove oil pan bolts and raise engine straight up until transmission is against floor pan.
15. Remove oil pan by first rotating clockwise (facing forward) to clear oil pump."

Hmmm. So why do you think the SM has a tool that works on the B-body and not the A-body. Misprint in the SM? The frames/crossmembers are different and *you cannot remove* the oil pan in an A-body while the engine is still in the car, thus the specific process written in the 1968 SM is to remove the engine from the Tempest models.

You can do it with engine in car, I did it, but not many will have the skill or patience to make the attempt to change an oil pump with the engine in the car - so I did not even suggest this and went with the 1968 SM of *Remove engine*.

How many 1968-72 oil pans/pumps have you removed from an A-body with the engine still in the car in the 45 year career as a master tech?


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## geeteeohguy (Feb 2, 2008)

Zero, Jim. Did it on a '67 A-body to replace the rear main and have done a '70 B-body. After that, I learned my lesson. Takes half the time and ends up with a much better finished result pulling the engine. IIRC, I don't think I pulled the pan all the way out of the '67, but dropped it enough to get to the rear main cap and torture myself with one of those Chinese finger rear main seal removal tools. It was decades ago. The oil pump pickup was the deal-breaker.
I missed the part that the OP's car was a '68 and was thinking of my own cars.


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