[supersport#69]

68 400

Are all the oil pans the same capacity? I was told from a member on here my pan isn’t right so wondering if it holds more/less.

My owners manual says 5.

[supersport#69]

This is the pan but if wrong I’m wondering if it’s still same capacity as original

[Sirrotica]

I'm going to answer your question based on my own experience working on the grease rack at a Pontiac dealer in 1970, and then continued my employment as a service tech for 45 plus years.

The pans fundamentally are the same, from 1955-1981, the small differences are baffles in the later pans. The differences in capacity are due to the markings on the dipstick, or gauge, as GM calls it.

Capacity for the early engines is 5 in the pan, 1 in the filter, which used the long canister with a cartridge 55-59. In 1960 they switched to the long spin on filter 5, and 1. 1967 only, 6 in pan, 1 in the filter. In 68 they returned to 5, and 1. Pontiac used the same basic pan, just changed the markings on the dipstick.

Hopefully this gives you the information you're seeking.

[supersport#69]

I could be wrong but I think I saw 5 quarts labeled on the dipstick.

[Sirrotica]

5 in the pan, correct, believe me, not everyone changes the filter every time. If you change the filter it's 6.

[Ben M.]

Ditto Sirrotica. Unless something has been modified or you are using an extra long filter it's always 5 in the pan and 1 in the filter. I change the filter every time and I top the filter off with most of 1 quart, screw it on, and add 5 quarts plus what's left of the 1 quart in the pan. Dipstick reads right at full on all +68 cars I've had.

I've known some guys who only change the filters every other oil change. Doesn't make sense to me, oil is much cheaper than an engine rebuild.

[Sirrotica]

The people that change filters every other oil change in my experience are someone that fancies themselves an engineer with more theoretical knowledge than common sense. The other people are ones are penny wise, and dollar foolish and are trying to get twice the value from the oil filter they purchased.

For what an oil filter costs, and how inefficient a full flow oil filter is, I choose to use a more efficient by pass oil filter on my own vehicles, ten years now using Frantz by pass filters has saved me more money by safely extending oil change intervals with a filter that is 10 times more efficient than the full flow filter is. Skipping oil filter changes will save you a few dollars today, and cost you thousands in the future. Even though I don't like the Fram filter construction, I do like their old advertising slogan, "Pay me now, or pay me later", lots of truth to that in my experience.

Many people try to extend oil changes by buying a synthetic oil and keeping the same inefficient oil filter doesn't truly work. The people that do oil analysis will tell you that just by changing to a different base that the oil is made from, has zero effect on how clean it stays after you pass the recommended oil change intervals. The full flow filters can't physically remove the fine abrasives that bond together and form sludge while making the oil more abrasive from contamination. By filtering to a very high standard using a by pass filter, the engine life has been proven to improve seven fold over using the standard factory designed filters and oil change recommendation.

Running the factory filter system past it's limitations and recommendations will harm the engine down the road, it's just false economy in my experience, but people do gamble on it, thinking they're saving money.

The oil analysis companies will tell you their experience is if you try to extend oil changes using synthetic oil and the same filter, the curve of oil deterioration and contamination swings quickly, the more miles that are piled on conventionally filtered oil. Better quality filtration is the key to extending oil change intervals safely, not just switching what base stock your oil is made from, or what additive package is used in the oils manufacturing.

[supersport#69]

What is a by pass filter?

I used Napa gold filter and 5 quarts of 10-30 valvoline vr1 zinc added

The car sat for close to a year getting body work, etc and only started maybe a handful of times. Recently we pulled the motor and replaced the rear main seal and pan gasket. It was pretty sludgy in the bottom of the pan. I was thinking I might just start it and run it 5-10 min a day then change oil/filter again after a few weeks to clean it out.

Would that be sufficient or should I add some type of internal engine cleaner? The engine has not been rebuilt so I want to preserve those internals.

[Ben M.]

Don't run it for 5-10 minutes only. You need to get it fully up to operating temperature and let everything circulate (driving it is best) and change the oil when it's hot.

[Sirrotica]

Here is a picture of a by pass filter that I use on my own vehicles:



Here is a schematic of how oil flows through it and re enters the crankcase:



Here is an link to an explanation of what it is and how it works:

https://www.machinerylubrication.com...ass-filtration

I don't like harsh engine cleaners to clean out varnish and sludge in an engine. Due to the fact when it gets disturbed it tends to accumulate in the lowest point of the engine (oil pan) and plug the screen on the oil pump. I'm speaking from experience and losing an engine having tried this. Using the by pass filter system to remove the buildup gradually is likely the safest way to clean out an older engine in my experience.

Running fresh oil and letting the detergents in the oil slowly remove dirt and then removing them from the oil is IMO the best course. Consider that all the accumulation in your engine was small enough to pass through the media in your conventional filter and when loosened will also pass through the media in a new filter. You need a filter that has smaller pores in the media that will remove the small abrasives from the oil and will not continue to let them circulate causing further wear.

Since you're going to be working the by pass filter harder than normal, you'll need to monitor it's quicker filling to capacity, and change it accordingly sooner. It's very simple to touch the outside of the filter after the oil warms up to see if it has plugged, if plugged the exterior will be cold to the touch. You can also use a pressure gauge plumbed into the by pass filter pressure side to monitor the pressure rise, indicating the filter is reaching it's holding capacity

That's my opinion from experience, it's your choice to implement better filtration, or stick with the inefficient filter the engineers stuck us with.

[68gtoMN]

Originally Posted by supersport#69

68 400

Are all the oil pans the same capacity? I was told from a member on here my pan isn’t right so wondering if it holds more/less.

My owners manual says 5.

If that was my comment, it was about the correctness of the style of pan (by years) only. The pans are all roughly the same. The point I made was in reference to the oil drain plug location on early pans vs. later pans. The pans themselves are otherwise identical in external dimensions. There may be slight differences in the internal baffling , dependent on year. They are, for all intents, identical.

[supersport#69]

Thank you. I did 5 quarts but added 4 oz of mmo and 4 oz of Lucas zinc additive.

I’m probably a little low but I’ll hav to check it. I have a hard time reading that stick.

[PontiacJim1959]

However...........

No one seems to be able to explain why the 1966 or '67 required 6 Qts in the pan and 1 Filter.

If the pan capacity is the same for all the years, what gives? I emailed Butler thinking they build enough engines to perhaps answer the question, but they could not. I was told that they don't use 40-50 year old pans and that all their builds get a new reproduction pan and the total, with filter, is 6 or 6.5.

I have seen here on the forum the dip stick having the tag "6 Qts". The AMA specs for the 1966 GTO shows 5 Qts + 1 Filt in their early release, but a later dated AMA spec shows 6 Qts + 1 Filt. I also have the Pontiac News Flash reguarding the use of 6 Qts = 1 Filt.

Another owner of a '67 GTO says the dipstick is stamped "6 Qts Cap" - and puts 6 Qts in the pan and 1 Filt.

Most all the Pontiacs I have owned were 1968 and up having 5 Qts pan and 1 Qt Filt.

So, are all the GTO oil pans 5 Qts + 1 Filt EXCEPT 1966/67 which were 6 Qts + 1 Filt.?

Is it possible that Pontiac was over filling 1 Qt in '66/67 due to their popularity and the racing image that they had that it was a way to protect Pontiac from warranty engine replacements (oil starvation on hard launches) by having that extra Qt added?

BTW - I will on occasion add a Qt of transmission fluid to the engine prior to changing the oil & filter. Add the Qt and let the engine idle and get up to temperature and let it run about 15 minutes. Then drain. Trans fluid is a good cleaner. I do this periodically on my 2015 Hyudai as well.

[Sirrotica]

From working on the grease rack in 1970 at a Pontiac dealer and rebuilding a 400 from a 67 Bonneville, I can tell you for certain that it's the same pan, but for some reason the engineers changed the gauge (dipstick) markings for 67. I have compared the 2 sticks side by side, and the markings are different.

Also when we changed oil and filter on a 67 if you didn't put 7 in, it read short after you started the car and ran it to check for a filter leak.

As much as I've been around Pontiacs, and dealerships I've never heard the reasoning why the change for one year, and then reversal back to 5 in the pan, and 1 in the filter in 68. Someone still living must know the reasoning behind the change for one year, but I have never found a creditable answer.

There were numerous changes in the engines from 66-67, and the very early engines with the newly designed heads had valve spring breakage problems, which was rectified during the 67 model year. But still no word on why the capacity was upped for 67 only.

I have noticed a trend in misinformation on capacities for the 67 engines in printed matter over the years. Used to be every time you looked it up back then, the printed matter was correct, 6 in the pan and 1 in the filter. Not so much anymore, many places list 5, and 1, for 67.

A few years ago I looked up Ames dipsticks, and noticed they list the same number for 67 through 79, which is incorrect.

So far, the reason for the one year change, remains a mystery.

[PontiacJim1959]

Originally Posted by Sirrotica

From working on the grease rack in 1970 at a Pontiac dealer and rebuilding a 400 from a 67 Bonneville, I can tell you for certain that it's the same pan, but for some reason the engineers changed the gauge (dipstick) markings for 67. I have compared the 2 sticks side by side, and the markings are different.

Also when we changed oil and filter on a 67 if you didn't put 7 in, it read short after you started the car and ran it to check for a filter leak.

As much as I've been around Pontiacs, and dealerships I've never heard the reasoning why the change for one year, and then reversal back to 5 in the pan, and 1 in the filter in 68. Someone still living must know the reasoning behind the change for one year, but I have never found a creditable answer.

There were numerous changes in the engines from 66-67, and the very early engines with the newly designed heads had valve spring breakage problems, which was rectified during the 67 model year. But still no word on why the capacity was upped for 67 only.

I have noticed a trend in misinformation on capacities for the 67 engines in printed matter over the years. Used to be every time you looked it up back then, the printed matter was correct, 6 in the pan and 1 in the filter. Not so much anymore, many places list 5, and 1, for 67.

A few years ago I looked up Ames dipsticks, and noticed they list the same number for 67 through 79, which is incorrect.

So far, the reason for the one year change, remains a mystery.

OK, thanks for your hands-on experience. No one seems to know why. I have a healthy collection of books, Pontiac engine build guides, and ton of Pontiac magazines I have read & collected over the past 35 plus years and not a one of them has ever mentioned a different oil pan - other than an aftermarket piece and of course the 1973 & up pan with baffle.

I would think that when the Pontiac engine build guides (both books & magazines articles) I have provide the reader with the "best" parts to look for and use on your performance engine build that one of them would have pointed out, "and if you can find one, get the 6 Qt 1967 oil pan." LOL

Thanks for clarifying the dipstick differences as I have not seen that info offered up showing the dipstick lengths to be the same, but the fill line being raised higher for the "extra" quart.

My thinking is that there was a big miscommunication between engineering and production. Maybe there was an intention to manufacture a 6 Qt pan but it was too late to make the modification to get to production. The AMA specs preceded production and of course were sometimes changed or supplemented during the production year.

My other train of thought is that a 6 Qt pan may have been scheduled for production on what was to be the Ram Air engine - perhaps a carry over from the 1966 XS engine and all the exhibition Super Stock racing done by the Royal Pontiac team. Their experiences were passed along to engineering and Milt Schornack did modify things to include the oil pans. Maybe a larger capacity was intended for the RA engines knowing that many would be raced.

My other line of thinking as I already pointed out, was that the extra Qt was to protect Pontiac. The extra Qt didn't hurt the engine, but gave an edge of protection when oil levels dropped and people didn't add oil until you hit the "add" line leaving 4 Qts in the pan which may have led to oil pressure fluctuations/starvation due to oil slosh when you had a car with 3.90-4.33 gearing and sticky tires and nailed the gas to the floor. So when the oil level hit the "add" line, you still had 5 Qts on a 6 Qt marked dipstick and this was enough to prevent oil starvation.

I can't think of any other mechanical reason unless more oil hung up in the heads due to a slow oil return, and this was cured in 1968 with the open chamber head design having larger/more oil drain? Never compared the heads for this to see if they are the same.

I guess it may be one of those Pontiac mysteries that only Pontiac or an engineer knew why the differences.

[supersport#69]

The oil pan might be the wrong year pan for whatever reason but it doesn’t have baffles in it and the stick only has 5 quarts stamped on it.

I estimate I’m at 5 quarts 8 oz total from what I put in. I used a Wix filter, Valvoline vr1 20/50 with zinc, 4 oz mmo and 4 oz Lucas zinc combo.

I’m going to check this morning. My fear is overfilling. I just replaced my rear seal and don’t want another leak.

Are leaks the main reason for not overfilling or?

[PontiacJim1959]

Originally Posted by supersport#69

The oil pan might be the wrong year pan for whatever reason but it doesn’t have baffles in it and the stick only has 5 quarts stamped on it.

I estimate I’m at 5 quarts 8 oz total from what I put in. I used a Wix filter, Valvoline vr1 20/50 with zinc, 4 oz mmo and 4 oz Lucas zinc combo.

I’m going to check this morning. My fear is overfilling. I just replaced my rear seal and don’t want another leak.

Are leaks the main reason for not overfilling or?

I don't see a problem. Keep in mind once the engine is running that you have oil being held up in the engine, so there isn't 5 Qts in the pan at all times, only when not running. But, if you feel more comfortable removing 8 ounces, then do it rather than drive down the road worrying and not enjoying the car.

I enclosed a photo of what 5 Qts fill in the pan looks like. This is the '73 baffled pan, but still the same 5 Qt pan. You can see where the fill line is at the back of the pan. Once running, that level will drop more.

Several issues can lead to main seal leaks. Here are a few that come to mind.

Too much internal oil pressure - not enough venting as you need at least one breather and possibly 2, but some will remove these or use valve covers having no breathers and that can cause leaks.

Using an aftermarket crank that has rough serrations on the crank journal which the main seal rides and a Viton seal is used. The rough serrations can burn up the Viton seal. These need to be smoothed down and made slick so they do not tear up the Viton seal and cause leaks.

Out of round oil seal groove in the block following align boring and then using the Viton seal. The Viton seal is made round and not forgiving if the groove is not perfectly round. This is where the Best brand graphite rope seal works best.

Improper install of the rear main seal - rope or Viton, usually not following the instructions.

It may not be a rear main, but the oil pan seal. Improper application. Did not use the corner tabs on the oil pan that provide a better clamping on the back of the pan rail. Need to re-torque pan bolts.

[Sirrotica]

If the addition of the extra quart was due to drag strip racing and acceleration they had better engines coming down the pipeline such as the round port headed cars beginning in 68 through 74. But that they dropped the oil fill back and never picked it back up, probably doesn't support that theory.

I know for a fact that starving the oil pickup in a circle track car, or a road course car is much more critical, and possible than going in a straight line, and starving them. It cost me more than one engine to verify that fact. The baffled pan that began in 73 works fine for left hand turns, not so much on right handers.

Since the 70s when I was racing, and working on Pontiacs as part of my own garage full time, I've tried to find out about the extra quart scenario. I've yet to encounter anyone with what I considered a valid reason might be.

One thing that doesn't make sense is all the cars with all the V8s no matter how low performance they were ( I had a 326 2 bbl Lemans, and a 326 HO Firebird, plus the 400 from a 67 Bonneville that I put in my 65 GTO) all used the 6 pan, 1 filter dipstick. If it was for performance engines only you'd think the beancounters would have made the move to save a quart in the mundane engines by using the 66 gauge/dipstick.

From that viewpoint I'm guessing it had to be reliability. The new 5 year-50,000 mile warranty that all the manufacturers were all coming out with at that time.

I was working still at the Pontiac dealership when the 67 Bonneville was brought in that I mentioned I got the core engine from, and I rebuilt and put into my 65 GTO.

The car had 24,000 miles on it and still had the original oil filter on it, rod hammering the woman wanted her 5/50 warranty to cover it. They promptly told her no way, and she paid to have a used engine installed. I got the core out of it to rebuild. It was a sludge ball, took me a bunch of Stoddard solvent in an old wash tub and wire brushes and rifle cleaning brushes to get it clean again, but it was free, and I had more time than money at that point..........

GM had just jumped from 12/12,000 warranty, to 5/50, so I can't help but to connect it to that. Although I'm not sure how 1 extra quart made the engines any more reliable, and make it to the 5/50 warranty point though.

[supersport#69]

I checked oil after roughly 5 quarts, 8 oz and it appears the level is just below the full line.

My motor has never been rebuilt. timing chain was replaced and I think water pump at some point.
The pan still had the two plates that reinforce the rear corners of the oil pan when we took it off so reused them. Viton one piece oil pan gasket was used and two piece viton rear seal.

I am tempted to dump a bit of oil because it was such a job to do that work.

If 5 quarts won’t hurt it then I’d like the piece of mind.

[supersport#69]

I went ahead and dropped about 8 oz just for my own sanity.

On the stick between add and full there are marks. What do those marks account for?