If you're running one of these on your bike I would remove it immediately. It's already been banned by many track day companies and you will not be permitted on a race track with this filter installed. I remember when this happened with Fram filters many years ago when they were blowing the threads of the filter and spraying the track down with oil. https://www.knfilters.com/recallkn204
I'm glad the OPer's friend had plenty of room to scrub off speed after the failure before he finally went down! Could have been so much worse...
I thought the whole top nut thing was such a great idea when I was first buying oil filters, then I realized it basically did nothing for me in my application. I'll have to make sure the one K&N oil filter I have left hasn't been recalled before I give it away.
2014 Forester XT, 80500 miles Last Change; Valvoline Full Synthetic 5W30 d1G2 Tokyo Roki 15208AA170 filter
We've seen this before, oil leaking from the filter at the nut they weld on. People have posted pictures showing the inside of the can where the nut is, showing cracks where the metal fatigued.
As far as I'm concerned that nut is one time use only, nobody should ever use the nut to tighten it down or take it off with the nut and then put the filter back on, it should be used to remove it and dispose of it afterward.
I think the nut is a stupid idea, given how easy it is to take a filter off if it's put on properly and the complications it introduces, more failure points. If someone reefed a filter on too tight I doubt the nut would help anyone at that point anyway, would probably just shear off the dome end.
K&N makes junk. A lot of "performance" parts are junk IMO.
K&N doesn't "make" anything. They are a brand name that is slapped on the product & box by the lowest bidder contract manufacturer. Same with STP. FRAM, Wix, Purolator all make their own filters (at least the ones with decent volume). The cats & dog low-runner models are generally purchased from China/India/Mexico.
Edited by DudeNiceRide (09/15/1711:58 AM) Edit Reason: added info