Well, you didn't get many replies so I will take a stab at it. I don't have a MB but I have a 1984 Ford Escort diesel that came from the factory with a bypass filter in addition to the regular full flow. Of course, it doesn't bypass the full flow filter but filters in parallel with it. A full flow filters down to about 30 microns. It is easy to manufacture a filter to filter finer stuff but it could clog up. A bypass filters much smaller particles and if it clogs no problem because the regular filter is still in operation. It is a fairly nice concept that should allow for extended drain intervals.
The Escort is now dead with a bad injection pump and I thought about taking the bypass filter off and putting it on another car. Finding any unused space to mount one is probably the biggest problem, then it has to be plumbed. Of course, on the pressure side you can just tee off where the pressure sending unit is. You will also need a non-pressurized return line to the valve cover or some other place. I thought it might be elegant to have the return oil feed onto the timing chain or gears. All in all, it seemed like a fair amount of trouble for the gain so I haven't done it. I know some people swear by them but most engines will last a long time with routine oil changes and conversative driving habits. Before the Escort died I was even thinking about taking it off just to gain some space in the cramped engine bay.
[Edited by johngray on 05-17-2001 at 01:19 PM]