This might interest those of you who choose to use the Mann W940/25 instead of...
05-03-2006, 06:17 PM
#11
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AAH and early AFC engines used a different filter altogether
When comparing the specs of the W930/21 with the W940/25, it's clear that the W930 flows more oil and filters better. I doubt the 6.4 oz extra oil make up for reduced flow with the non-LL filter. The LL filter medium will also hold up better over a longer oil change interval.
The W930-21 is not the filter Audi originally specified for my AFC, but is already the updated recommendation.
It also appears that the W930/21 is the only VW/Audi OEM oil filter with a 3 bar bypass pressure valve that MANN makes. All the others have a lower setting. Why this is, I doubt we will ever find out.
The W930-21 is not the filter Audi originally specified for my AFC, but is already the updated recommendation.
It also appears that the W930/21 is the only VW/Audi OEM oil filter with a 3 bar bypass pressure valve that MANN makes. All the others have a lower setting. Why this is, I doubt we will ever find out.
05-03-2006, 08:09 PM
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Yes -- the filter may be running in bypass mode to early and too often
When the engine oil is very cold and the oil is still thick, oil pressure will be high and the bypass valve will open to ensure (partially/mostly unfiltered) oil flow. A 2.5 bar bypass pressure relief valve will open earlier than a 3.0 bar bypass pressure relief valve.
05-04-2006, 10:07 AM
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And I'm not saying you shouldn't have used them or not keep using them
I'm only pointing out the data and specs that MANN supplies.
We all overestimate the effect an oil filter has anyway. There have been test done in cars that are running without oil filters, and these tests suggest that this is do-able without ill effect. Some cars did not even have oil filters, like the original VW Beetle.
We all overestimate the effect an oil filter has anyway. There have been test done in cars that are running without oil filters, and these tests suggest that this is do-able without ill effect. Some cars did not even have oil filters, like the original VW Beetle.
12-23-2006, 11:43 AM
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from that it looks like 940/25 is the better filter.
makes sense it has slightly less pressure / flow, it is a larger capacity container.
as for bypass pressure w/ cold oil, it sounds better to have the 940/25 and I'll take the larger filtration element, larger capacity, and finer straining over the smaller one anyday.
all the negatives you mention are just your assumptions. You list facts w/ Mann's specs (thank you) but add your assumptions on what they mean for the Audi.
A larger filter (6oz is ALOT bigger btw) gives more surface area and more cooling- from additional oil and additional surface area of the filter itself.
I don't agree but it is a thought provoking topic, thanks for posting your thoughts and info.
as for bypass pressure w/ cold oil, it sounds better to have the 940/25 and I'll take the larger filtration element, larger capacity, and finer straining over the smaller one anyday.
all the negatives you mention are just your assumptions. You list facts w/ Mann's specs (thank you) but add your assumptions on what they mean for the Audi.
A larger filter (6oz is ALOT bigger btw) gives more surface area and more cooling- from additional oil and additional surface area of the filter itself.
I don't agree but it is a thought provoking topic, thanks for posting your thoughts and info.
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