I have a 2019 Crosstrek with about 25k miles. I put in a K&N air filter when it was new and basically never looked at it again until yesterday. The car gets ordinary street and highway driving, no excessively dusty or dirty areas, and the filter didn't look super dirty when I checked it yesterday. According to K&N the cleaning interval is 50K miles, but I decided to take it out and clean it anyway. Since you have to let it dry after washing it, I put in a regular filter (Champ AF5293) for the meantime.
But.
First: the intake duct was noticeably oily. Not super-caked with oil, or anything like that, but not dry either. K&N claims these filters do not shed oil, and do not foul sensors. But it's clear to me now that they do shed oil, and although I have not had any sensor problems I can now see how that could happen.
Second: the car performs better with the paper filter. I wasn't expecting that; it surprised me. I know a new, clean K&N will have better flow-through than a stock filter, so I can only guess the 50k cleaning interval is wishful thinking and I should have cleaned it 5-10k ago.
So I'm now thinking K&N's marketing claims are not entirely credible, and I'm considering just switching back to paper filters from here on.
But.
First: the intake duct was noticeably oily. Not super-caked with oil, or anything like that, but not dry either. K&N claims these filters do not shed oil, and do not foul sensors. But it's clear to me now that they do shed oil, and although I have not had any sensor problems I can now see how that could happen.
Second: the car performs better with the paper filter. I wasn't expecting that; it surprised me. I know a new, clean K&N will have better flow-through than a stock filter, so I can only guess the 50k cleaning interval is wishful thinking and I should have cleaned it 5-10k ago.
So I'm now thinking K&N's marketing claims are not entirely credible, and I'm considering just switching back to paper filters from here on.