RT is completely right that the oil keeps on being displaced by more oil after it moves through the filter. My filter is slightly lower than the return into the block and I guarantee it works, otherwise it wouldn't have hot oil in it. I'm also 100% sure that if I put a 20 foot long return hose on it and stood in the back of my truck on a ladder holding the hose up above my head I would be coated in oil in a matter of seconds (I'm not going to test this ) Once again, it's the flow that's reduced not the pressure, it just appears that there is no pressure in the post-filter line because it offers no restriction.

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1985 300D Turbo ~225k
2000 F350 (Powerstroke) 4X4, SWB, CC, SRW, 6spd ~148k
1999 International 4900, DT466e (250hp/660 ft/lbs), Allison MD3060 ~73k

You won't get one drop of oil unless and until pressure builds up in the 20 ft. hose, downstream of the filter. This may happen, eventually, but in order for it to happen, the oil must back up into the filter, and the flow must be dramatically reduced, so that the filter effectively provides a limited pressure drop across the filtering element. Then, there might be some additional pressure available downstream of the filter to push the oil up 20 feet.

You fellows need to understand the basic theory on pressure and flow.

In order to approve this message you had better continue on course and conduct the aformentioned test, with photo documentation and post results. We all know of scientific bias, and so you will need to find a unknowing , unrelated volunteer to aid you with the test by holding the end of the oil line over their head. For safety's sake chose a subject of smaller physical stature with out direct access to possible weapons. For the sake of your Mercedes, inform the subject that Andre the giant (or sasquach, who may be a distant relative to you) loaned you his car, and then the perhaps oil coated subject will not damage the vehicle, if the test is a success.


The above is for humor only and is not intended insult anyone. The Palm Beach society of upstanding uphill bypass filter users has sponsered this infomercial. Please direct all communications to Dr. Heywood Yablome.

"You fellows need to understand the basic theory on pressure and flow"

Brian,
We might as well agree to disagree on this. The fact that you keep talking about the oil "backing up in the filter" and "flow must be dramatically reduced" indicates quite clearly to me that you don't understand what you are talking about. I did well in Physics and spent 5 years building and maintaining industrial hydraulic systems some years back so I kinda think I have some experience in this area. I wish I could explain it to you better. Wasuchi has it right on.

This has been a good thread but its a bit off topic right now. This is my fault too for not leaving well enough alone but I just can't help myself. RT

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When all else fails, vote from the rooftops!
84' Mercedes Benz 300D Anthracite/black, 171K
03' Volkswagen Jetta TDI blue/black, 93K
93' Chevrolet C2500HD ExCab 6.5TD, Two-tone blue, 252K

Well, I can't help myself either. But, I'll close it with the statement that the bypass filter manufacturers obviously don't know what they are talking about either, because they clearly recommend that the return line should not rise above the bottom of the filter. Maybe they, too, are concerned with no pressure in the return line?