Pro: Put K&N Filter on. Replace BMW OEM filter. Engine suffers catastrophic failure. Dealer: "Hmmm...looks like your filter element failed and was ingested by the engine; hoho, what's this?! K&N?? Sir, your warranty is void and you are snookered." You: "But I asked on an internet bimmerboard and they said it was ok?!" Dealer: "Hahahahahahah, good one. Next."
Con: Keep OEM filter. Um, there are not other cons here. Car is under warranty, end of story.
Kind of a no brainer to me? Don't do it till your warranty expires. YMMV. :dunno:
BMWs have large airboxes and filters. The power increse from a K&N filter on an otherwise stock motor will be very very small or zero.
Oil will migrate off of the filter and work its way downstream. It will contaminate all sorts of things. I had this happen on my '94 Dodge Pickup. The truck was off road a lot and I got the K&N to save on paper filters. Big mistake.
On a BMW there is a chance the oil get will into the MAF sensor. If the dealer finds it full of oil, they are can charge you for the part, even if the oil isn't what made it fail.
A forum community dedicated to BMW owners and enthusiasts. Come join the discussion about Bimmerfest events, production numbers, programming, performance, modifications, classifieds, troubleshooting, maintenance, and more! Bringing the BMW community together.