just a thought...this is what I didd on a hydraulic system....tee into the drain plug hole and run a sight tube up the side of the engine???....btian 77 ele 455

I don't want to be a worry wart, but I just don't feel comfortable relying on what we call "Conventional wisdom" when it comes to something as critical as the oil level in our heavily taxed engines. I am looking for a definitive way to measure the actual oil level in the pan.

The conventional wisdom of adding 5 quarts at a change and then calibrating the dip stick to that level is based on a bone stock system. Dial ahead 40 years and many coaches now have different cooler lines, aluminum radiators, external oil coolers, etc., all of which add to the volume of the system upon which that conventional wisdom is based. With only 3 quarts in the sump of a stock system full, a relatively small change in system volume, say one quart, has us driving down the road with just 2 quarts in the sump at what that calibration would call the full mark and at the add mark there is only one quart of oil in the sump! Too little for my sense of well being for sure.

Think a one quart change is system volume is a lot? A Derale 15550 fan assisted external engine oil cooler, for example, holds 19.6 oz or nearly 2/3 of a quart all by itself. I don't know how much additional oil it takes to fill the engine oil cooler in an aluminum radiator over a stock one but it certainly looks like it would be significant in the scheme of things. A larger oil filter that some are using might well take several ounces more than the stock filter. Start adding all these seemingly little things together and we might well be running seven quart systems rather than six quart systems.

We can certainly guess and adjust accordingly but we know if we are off by having too much oil in the system the excess will be burned off quickly and if too little we are at risk of damaging bearings and not pulling heat out of the engine properly. I would prefer to know exactly where full really is on any given combination of engine, radiator, lines, coolers, etc.

Any one have a thought on how to do this?

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







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Brian,

By the way, here's my photo of 3q. in the pan:
http://www.gmcmhphotos.com/photos/455-oil-pan-capacity/p10644.html

And here's the best photo I've got showing that the 3q. corresponds to the
FULL mark. Not quite so obvious is that the rod caps will just clear the
oil pool at that level -- avoiding the foaming and power loss that would
result if they became submerged.
http://www.gmcmhphotos.com/photos/455-oil-pan-capacity/p10810.html


All of which says that your temporary sight gauge should show FULL at
4-3/8" below the pan flange -- IMHO.

Ken H.

Guys, You are making this an unnecessary complex issue. The numbers and procedure I gave you is from my unmodified 455. The dipstick tube and dipstick on mine are still painted OEM blue. If you drain the oil and replace the filter, 5 quarts will fill it up to the full line. I use 1 quart of oil in 6000 miles so the oil is not being beat to death and foaming at that level. I have NEVER put 6 quarts in it and do not care to try it.

Having oil in an oil cooler or coolers does not really affect how much you drain because that oil is stuck after the oil pump and before being forced on through the filter and the engine. There is no path for air to enter that part of the system to allow oil to drain. So forget about that.

Drain the oil, replace the filter, and add 5 quarts of oil. Run the engine to fill the filter and shut it down. Wait 5 minutes and read the dipstick.

THAT IS THE FULL MARK.

Guys, You are making this an unnecessary complex issue. The numbers and procedure I gave you is from my unmodified 455. The dipstick tube and dipstick on mine are still painted OEM blue. If you drain the oil and replace the filter, 5 quarts will fill it up to the full line. I use 1 quart of oil in 6000 miles so the oil is not being beat to death and foaming at that level. I have NEVER put 6 quarts in it and do not care to try it.

Having oil in an oil cooler or coolers does not really affect how much you drain because that oil is stuck after the oil pump and before being forced on through the filter and the engine. There is no path for air to enter that part of the system to allow oil to drain. So forget about that.

Drain the oil, replace the filter, and add 5 quarts of oil. Run the engine to fill the filter and shut it down. Wait 5 minutes and read the dipstick.

THAT IS THE FULL MARK.

Guys, You are making this an unnecessary complex issue. The numbers and procedure I gave you is from my unmodified 455. The dipstick tube and dipstick on mine are still painted OEM blue. If you drain the oil and replace the filter, 5 quarts will fill it up to the full line. I use 1 quart of oil in 6000 miles so the oil is not being beat to death and foaming at that level. I have NEVER put 6 quarts in it and do not care to try it.

Having oil in an oil cooler or coolers does not really affect how much you drain because that oil is stuck after the oil pump and before being forced on through the filter and the engine. There is no path for air to enter that part of the system to allow oil to drain. So forget about that.

Drain the oil, replace the filter, and add 5 quarts of oil. Run the engine to fill the filter and shut it down. Wait 5 minutes and read the dipstick.

THAT IS THE FULL MARK.

Adrian,

The photo you should look at is http://www.gmcmhphotos.com/photos/455-oil-pan-capacity/p10800.html
which more accurately shows the relationship of the various parts (disregard the un-trimmed dipstick tube).

There, you'll see that the two rods just right of the dipstick tube are near the bottom of their strokes and that they're at least 4" below the pan flange. In other works, they swing to within less than 3/8" from the 3 q. oil pool. If there's 4 q. in the deep end of the pan, the rods will definitely be submerged.

I apologize to everyone for having not anticipated all these factors when I originally made and posted the photos -- I could have made them more clearly and less ambiguously display the parameters of interest.

Ken H.
Americus, GA
'76 X-Birchaven w/Cad500/Howell EFI & EBL,
Manny Brakes & 1-Ton, etc., etc.
www.gmcwipersetc.com

Seems like replacing oil shouldn't be that complicated. I have an external oil cooler with about 4ft of 5/8" line tieing it in to the aluminum radiator cil cooler.after an initial oil fill I just drained the oil refilled with 6 quarts and a new filter adjusted the length of the dipstick too read full and I was done. I have about 1000 miles on the oil this trip and the dipstick still reads full. By the way I have 2 drains on my pan. I think I am close enough not to worry.