Thanks Jim, Matt and others that have responded so far. The root cause issue here is that the only base line we seem to have is the factory manual that says the system takes 6 quarts when filling a new, dry engine. That is the only place and time that it seems we can truly calibrate the dip stick.

If any modifications are made, then the dry system capacity changes and 6 quarts will no longer reflect full on the dip stick as the initial fill would have to account for the additional system capacity. That is the case we experienced, JimH, when filling the Clasco after you secured the previously loose dip stick tube at what you determined to be the correct factory location and installing the new S&J engine. When filled with 6 quarts dry, the dip stick showed the oil level about half way between the full and add marks. That made sense to me given the larger capacity of the cooler in the aluminum radiator and the external oil cooler. So, the correct dry fill amount given that system configuration is apparently 6.5 quarts.

The case for the Royale is not so straight forward. Since I found its dip stick tube was also loose, there is no reliable base line to know the actual dry fill capacity of that system. The Royale is configured the same as the Clasco, but without the external oil cooler, so one would think the dry fill capacity would be less, likely closer to the 6 quarts the factory specifies.

But as Matt points out, that specified 6 quart capacity for a stock configuration is not necessarily correct, either. Empirical data from his dyno tests say 6 quarts is too much and some of that excess will burn off quickly. The other conundrum here is KenH's measurements which show that full on the dip stick occurs when there are only 3 quarts of oil in the sump end of the pan, an additional 1 quart sits in the shallow front end of the pan, around one quart sits in the filter and the rest is somewhere else in the system.

Come oil change time we think we need to add back 5 quarts to bring the system back to full. And, we think none of the oil in the cooler(s) and lines will drain out so that means something around one quart goes into the filter leaving four quarts to go into the sump end of the pan. But, if that is the case then KenH's measurements would say the dip stick would read one quart OVER filled unless one of those quarts really did drain out of the cooler(s) and lines.

The bottom line is we currently have no real base line to go on once we pass the initial dry fill (and even that may not be correct). I think we need to develop a reliable way for all of our owners to know when they have the proper amount of oil in the engine no matter what modifications may have been made over time to the system capacity, the dip stick or the tube. That is what I am seeking to find.

I am wondering if all these variations may be partially responsible for the number of newly installed engines that have reportedly gone south no matter who the engine builder was. As I said in the earlier post, if KenH's measurements are correct and 3 quarts in the deep end of the sump is where the factory says is full then it would not take much of a change in system capacity, or a change in the effective length of the dip stick tube, or a mistaken previous calibration of the dip stick itself, for the oil in the sump to reach a critically low level.

Hence, I remain convinced that we need to come up with a reliable way for every owner to really calibrate the dip stick based on something other than how much oil we put back in after an oil change or by trying to find the inflection point on rate of oil consumption. So far the only seemingly certain way to do that is to measure down on the sump end of the pan the 4.5" from the flange KenH's photos show should be full, drill a small hole and add oil until it starts to dribble out. Then, calibrate the dip stick at that point and seal the hole. I am hoping someone can come up with a less invasive, but equally repeatable and reliable, method. Thanks for all the band width.

Jerry
Jerry Work
The Dovetail Joint
Fine furniture designed and hand crafted in the 1907 former Masonic Temple building in historic Kerby, OR
Visitors always welcome!
glwork@mac.com
http://jerrywork.com
================

Message: 2
Date: Sun, 8 Feb 2015 09:54:23 -0800
From: James Hupy
To: "gmclist@temp.gmcnet.org"
Subject: Re: [GMCnet] Dip stick calibration question
Message-ID:

Content-Type: text/plain; charset=UTF-8

Jerry, once the system is full, including the filter, lines, radiator
cooler, auxillary cooler, and the front of the oil pan that some say does
not empty when changing oil, what SHOULD remain in the deep part of the
sump if the system is full, is 5 quarts. Drain the oil from the sump and
unscrew the filter, catching it's contents into the same oil pan. Measure
that amount, and replace that amount. Mark the stick.
Jim Hupy
Salem, OR
78 GMC Royale 403

Date: Sun, 08 Feb 2015 10:49:51 -0700
From: Matt Colie
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] Dip stick calibration question
Message-ID:
Content-Type: text/plain; charset="utf-8"

This is referenced to the quote glwgmc (Jerry Work) wrote on Sun, 08 February 2015 11:34

Jerry,

You are correct to be concerned.
In the case of the Olds 455, the stated refill capacity is definitely wrong for an engine in stock trim. I when about this long and hard early in my
ownership. At the fill mark, the top quart goes away fast. Much of it through the crankcase vent system. (I only say most because I can't prove -
all.)

While the lube oil handling may have been modified over the years, if it does not completely drain during a lube oil service, it does not matter.
This is something that will have to be determined on a individual basis.
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One way is to borrow a known good or original dipstick and see what your system says. Any other mods that have been made over the years have no effect on what a known dipstick will read. If yours doesn't agree- remark it. Go to a rally and try a couple.

Here's the photo Skip found, along with an extract from a message I sent to someone off-line yesterday:

While looking for those photos, I happened to notice http://www.gmcmhphotos.com/photos/455-oil-pan-capacity/p10800.html There, the relationships and measurements are much more clear than in most of the views, despite the dipstick tube having not yet been trimmed.
Notice that:

(1) The oil pickup extends down to about 7-1/4", putting it near the 7-1/2" you postulated for the depth of the pan.

(2) The horizontal baffle (presumably intended to suppress ripples on the surface of the oil and missing from a lot of engines) is right at 4-3/8".

(3) The two rods to the right of the tape are near the bottom of their strokes, and are at about 4" below the flange -- just enough to clear the oil pool at 4-3/8" (3q.).

It's all pretty convincing to me. And I still don't know where that 5th quart of oil hides unless it is that the front section is actually almost empty when the engine shuts down and is only slightly refilled by drain down. That would allow for 3 in the deep end, 1 in the shallow end, and 1 in the filter.

Ken H.