I have had k&n for years in automotive apps and haven't experienced the shrinking yet. These are all the modern rectangular shaped ones I'm using. Are you using the k&n cleaner/oil?

Hmmmm. Well, keep driving then. LOL.

BTW: More common to have a 10yr old K&N on a boat, then a car.

I just picked a number, but it should work.

Don't use the filters or cars anymore. I still have a truck with a K&N that I haven't even started in 3 yrs. Filters at least 10 yrs old. I'll pull it out and see how it looks.

I only have 1 customer that won't let me throw their K&N out. Bunch of years ago I noticed I was replacing more MAF's on vehicle's with K&N's and then I made a stand and got rid of them....Again, on MAF vehicles...especially those where the filter is close to the MAF. I continue to use them here and there on some carbureted engines.

I have one on my boats because we are on dirt roads that turn to dust roads during the summer. Boat get's put back on trailer each use, and gravel dust is very coarse !

Tell me about it. I live on gravel roads. Almost not even worth washing the car. Covered with a layer of dust every time I leave home. They do oil some of them a couple times a year, lucky me.