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      02-09-2012, 09:57 PM   #23
Lieutenant Colonel

Drives: 2011 328i Wagon
Join Date: Feb 2011
Location: Westbrook, Maine, Port Charlotte, Florida

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Originally Posted by John 070 View Post
I actually have the actual detailed report but I don't feel like finding it, it's on a hard drive somewhere. The machine that tested the filters is industrial and cost hundreds of thousands of dollars. It was a guy who was curious if he should us AC Delco for his turbodiesel, or K&N.

A BMW is not just any old car, for whatever reason, BMW puts a Mahle Knecht in from the factory. It's simply amazing that someone thinks they can do BMW 1 better by jumping on and getting a different filter for $40 that they can clean and reoil and use forever. It's like X-Files, "I want to believe." Well, it's your car, go ahead and drop that K&N bad boy right in there!
But note that BMW also includes a K&N filter with the OEM Performance Intake.

Generally speaking, I am not a fan of K&N filters, but I think the MAF oiling problem is more of an issue than the probably somewhat reduced filtration. What extra dirt that gets through is still probably too small to do any damage, ends up in the oil and captured by the oil filter anyway. The charcoal filter in the BMW airbox pretty well eliminates the MAF issue as long as it is in place. And probably captures some of the extra dirt too.

But all THAT said, I would not have bothered to buy a K&N to use in my stock intake. It came with the new one, and seemed to be properly oiled, so I used it.
'11 328! Touring - Tasman on Chestnut, 6spd manual, factory upside-down "i" option
also '17 VW GTI Sport, '95 Land Rover Discovery, '91 Volvo 940GLE 16V, '74 Triumph Spitfire