I just recieved this from Mahle.

This type of oil filter, which is comprised of pleated paper (upper half) and cotton depth type media (lower half) is rated at 22 microns nominal on the pleated paper media. The depth type media because of it's design and material will generally be a finer filter.


I'm on the fence between Mahle and a Turkish Fram

It's called a bypass filtration system for a reason.
 

You've made two critical mistakes here. One is assuming it is not a good idea for the oil going through the upper portion of the filter to go back to the pan. It was engineered that way for a reason and results in better filtering than simply passing all the oil through the filter once on its way into the engine. Oil is recirculated many times through the upper section and returned to the pan resulting in cleaner oil before it gets pumped into the engine. That's why the upper part of the filter is a finer filter than the bottom part. The bottom part of the filter is more coarse because it expects to receive pre-cleaned oil. Disabling the bypass filtration will result in much dirtier oil.

Secondly just because you blocked the return passage for the bypass does not force more oil into the engine. The oil filter has two sections separated by a seal and disabling flow back into the oil pan simply disables the bypass and doesn't put more oil into the lubrication system.

Read section 18-005 of the service manual for a description of how the oiling system works and then Google 'bypass oil filter' and read up on the concept. This document http://www.dtsc.ca.gov/PollutionPrevention/upload/bypass-oil-filters-fact-sheet.pdf does a good job of explaining the concept. Mercedes was nice enough to put a fantastic filtering system on your engine that is only offered as an expensive aftermarket add-on for other engines. Don't modify it without fully understanding what you are doing.

Incorrect. Blocking the bypass section DOES put more oil into circulation. Instead of pumping through the bypass and into the pan it pumps through the full flow and into the lubrication system.

Look at the disassembly pictures of the oil filters and try and tell me again it actually cleans the oil.

The answer to that could be to have the oil filter analyzed when it is changed to see how much waste has been trapped. I do know that when I send in my oil to get tested that something is keeping it clean and doing a good job of it.

An actual test could probably be comprised where a known level of contaminants is introduced into a motor with fresh oil and the oil then analyzed after a fixed length of run time with both filter configurations. Since I'm not willing to alter the bypass on my engine I won't be volunteering to perform the test. If someone is willing to do the test I'd be very interested in the results. In the meantime I'll be relying on a filtration system designed by people who know way more about it than me and field tested in hundreds of thousands of vehicles.

Certainly not the loosely packed cotton gin waste and its dirt, rocks, sticks and insects. It might absorb some contaminants but it sure isn't filtering anything meaningful. The cotton is precontaminated before you even put it in the engine, dirt definitely isn't something I want my oil mingling with. It is loosely packed and the orifice is only ~1/16" so the oil moves slowly enough that it can form channels around the cotton, completely defeating the reason for its existence.

Amsoil's EaBP90 is over 99% efficient at removing 5-20 micron particles and 98.7% at 2 microns. I seriously doubt dirty cotton can come remotely close to that.
http://www.fourseasonsynthetic.com/p...p90_250pxw.jpghttp://www.allsyntheticsgroup.com/im...test-graph.gif

Not only that but it adds an additional 1qt oil capacity to the engine.

I have a wix in my var now. Sounds like Ill be sticking to them.

Now I don't know WHAT to do.

When it comes to second guessing the mb engineers I am very reluctant.

I would like to be confident that the filters I use don't put junk in the oil though.

Tom W

Why are you so sure that the bypass media is precontaminated in all filters except the Turkish Fram?

I'm investigating with Fram and Mahle.

Take them apart and you'll see. The Turkish Fram is the only one taken apart that uses something other than cotton gin waste.

Seems like they've been using the gin waste contaminated filters for 25 yrs and going 200-300-400K miles i seriously doubt mb would build something that isn't gonna do some good the idea of more oil going thru the engine isn't a concern if u use 5w-40 synthetic anyhow i doubt the flow rates back then aren't nearly what they are now anyhow i agree amsoil stuff or something like that is probaly better but something i bet is better than nothing at all.. besides i seriously doubt it would shorten the life or do any difference in power or functional wise degrade performance so blah i'll get whatever is at a decent price which seems to be bosch or mahle or mann at moment. The fuel filters by wix are like 7-8$ i'll stick with those but just thinking about it for a bit i really doubt it matters since the removal of the bypass part is a new thing i'd tend to side with the old vs the new concepts..

Do a search- one of the members cut apart several brands of filters and found what I guess is raw cotton as it comes off of the plant when picked. I had other parts of the plant and occasional bugs in some of them. Better to look for yourself.

The companies can tell you how many microns the pleted paper part will filter but none seem to know how many micron the by pass part of the filter will filter down to. I seems as if they followed the OEM spec but never tested them.

Has anyone tested them?
 

I understand it is disturbing to find a boll weevil carcass in something that is supposed to keep your engine clean but has anyone found out if it really makes a difference? Has there been a test that shows decreased filtering efficiency due to contaminated media?

Even if the commonly available filters are not as good as they should be or used to be I still don't see how disabling bypass oil filtering (as suggested by another poster) would help that. Since bypass filtering is a multiple pass system it should help to mitigate the effects of poor quality filters. Of course I do not have test data to back that up so it's just my opinion for whatever that is worth.

What I want to see are some oil analysis tests of 5000 miles on a 617 with synthetic oil using a Turkish Fram filter, a Bosch Filter, a Hengst Filter, and a Dealer Filter. Just to see if there is any real difference in how clean the oil is between the three. In "theory" the Fram should be cleanest, as it uses the most physically clean material to begin with, and its much more densely packed.

That would be tough for someone like me who seldom drives over 5000 miles a year and I bet I change my oil at least 3 times a year (if it starts looking really black I change it).
The companies that make these filters should be able to tell us how many microns both parts of their filter will filter out. I dose not appear that they actually know (except for the wix which is all pleated paper) the performance of the bypass part of their filters.
For myself I am going to install a bypass filter system and I am waiting for the filters to arrive right now. That way I will not matter what the upper part of the stock filter dose.