Originally Posted by M3takesNYC
Well you are disregarding the entire concept of an oil filter. The whole point is that it can have bigger "holes" in the filter but the oil itself acts as a filter to "stick" to particals. So instead of a mechanical filter if you will, its a oil film filter that lets air through but sticks the dirt and particals.
So yes you can have bigger flow with not much more dirt go through due to the oil. That is why putting an oiled filter back in under oiled is devestating
I have 5 new BMC fitlers i replace every 10k miles as I don't like to clean and reoil mine.
The non-oiled filters obviously flow less as stated
Give me a break, you think I don't know about the principle of an oiled cotton and gauze filter.
If they filter so well, why is it recommended for you to use a filter sock on motocross bikes or ATV's? The reason is that an oiled cotton and gauze filter will let in enough dirt to dust the engine on those machines!!! I have seen it first hand!!!
You go ahead and use your aftermarket filters if you like, for maybe a 2HP gain I think I will choose to forfeit the 2HP and protect my engine!
The only filter upgrade I recommend is using the Euro Filter on 08 - 09 north american M3's
P.S.: I have done hundreds of hours of technical training on oil, fuel and air filtration! The engines I work on are close to $1million a pop so the company I work for is big on filtration and engine cleanliness in general!