This is a rehash of an argument that is at least 2 or so years old. And, in this case the logic provided by Big Red is really the only logic. The other arguments being presented are based on emotional responses to "discoveries" of what seems to some customers to be filler material in the by-pass section of the filter that is objectionable.

First, MB supplied filters are purchased and distributed based on the specification MB generated, and Big Red published an excerpt from, from MANN, Hengst, Bosch, and others, thus they are called OEM suppliers or manufacturers. The idea is that if they supply to MB per MB's specification, they should be able to market the same product to other filter distributors and still be recognized as suppliers of this product to MB.

To understand why this junk in the filter is not objectionable in and of itself for technical reasons, you have to understand the function of the by-pass filter. That has been explained above, but to reiterate, the flow rate through the by-pass filter is trivial. There is very little differential pressure across the media and the idea is the oil spends some "dwell time" in this volume of filtering media, allowing the particulate material to get caught or just drop out of suspension. The various sized chunks of junk allow for small cavities to form to hold the oil for brief periods, slowing it down and presenting lots of surfaces for oil contaminants to adhere to, while preventing any channels for forming.

A much greater concern is that the oil filter seals along the ID of the filter are correctly sized and retained. If the by-pass filter section is not sealed from the main flow section the by-pass filter sees a much greater differential pressure and the whole by-pass element can collapse. In that case a structural failure may occur and the evil by-pass filter element contents could be dumped into the main flow path leading to the bearings and other smaller, readily clogged flow passages. And in this instance you don't need little bits of grit to cause the engine to fail.

Overall, Big Red has headed this down a path seeking technical answers from the manufacturer concerning the manufacturing/materials selections for these filters that may allow this discussion to be closed. In the end, we can buy whatever filter brands we might want. But we can at least know the technical basis for what we are finding in the by-pass filter media, and then choose to accept it or presume to know what is better. Jim

Jim

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Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)