Spark plugs should be covered on every warrenty where they fail before their reccomended service interval which is often longer than the warrenty period these days.
Oil of any kind, animal, vegetable, or miniral can FU a MAF.
Most of the K&N related MAF isues I have heard of have been related to recharged ones where the asshats didn't read and/or follow the instructions and tried to do a recharge in < hour, and/or used more than the reccomended amount of oil. The filters have to be completely dry before you oil them and most idiots won't wait that long.
I've done enough now that I often end up with a correctly coated filter before the reccomeded amount by a 1/0th of an ounce or 2. I have 3 MAF cars with them, and 5 or 6 recharges and never an issue.
I like them and was thinking about building a cardboard heat shield for a couple of them.
