During a just-completed oil change, as I was wiping the threaded pipe in preparation for installing a new filter, I felt it turn(!) and was able to unscrew it partway with my gloved fingers. I tightened it again with a 3/8" breaker bar, an adapter and a 27mm socket. The fitting's head's flats are very shallow, requiring one hand to push the socket home/flush, while the other tightens. This was all done from below the right-front inner-fender plastic stone shields, with the wheel removed.
I have a theory as to why this may have happened now. The filter I used previously was a K&N (image 1), with a 1" hex-bolt-like protrusion, which I utilized with a box-head wrench to unscrew the filter, and it worked pretty well. This procedure, though, may have broke loose the threaded pipe as well as the filter.
I typically use a plier-type filter wrench (image 2) that squeezes/deforms the canister, slightly relieving the rubber ring of pressure on its sealing surface and thereby reducing the torque on the pipe's threads. In fact, I prefer this style of plier specifically because it seems to require the least amount of torque/effort to break the old filter loose. I may not have appreciated an additional benefit of this practice.
I would suggest checking that your fitting is tight the next time it's exposed.
Images 3 and 4 are of the threaded pipe/fitting - halfway unscrewed, and tightened again, respectively.
1: K&N filter with hex-head protrusion
2: "Crusher-style" oil filter removal pliers - not used this time...
3: fitting unscrewed
4: fitting tight again
I have a theory as to why this may have happened now. The filter I used previously was a K&N (image 1), with a 1" hex-bolt-like protrusion, which I utilized with a box-head wrench to unscrew the filter, and it worked pretty well. This procedure, though, may have broke loose the threaded pipe as well as the filter.
I typically use a plier-type filter wrench (image 2) that squeezes/deforms the canister, slightly relieving the rubber ring of pressure on its sealing surface and thereby reducing the torque on the pipe's threads. In fact, I prefer this style of plier specifically because it seems to require the least amount of torque/effort to break the old filter loose. I may not have appreciated an additional benefit of this practice.
I would suggest checking that your fitting is tight the next time it's exposed.
Images 3 and 4 are of the threaded pipe/fitting - halfway unscrewed, and tightened again, respectively.
1: K&N filter with hex-head protrusion
2: "Crusher-style" oil filter removal pliers - not used this time...
3: fitting unscrewed
4: fitting tight again