Everytime I go to change my oil filter it is barely tight. I put it on tight, but it backs itself off. In the six years that I spent pulling wrenches I never saw that happen. Especially on a diesel. They always seemed to weld themselves on. Is is the vibration?

 

I don't know what causes it but i hav e seen it also, I have seen between changes a drop of oil on the bottom of the filter, reach up and I can hand tighten it. Weird but I know when I put em on they are a lot tighter than that.

 

I think it has alot to do with the gasket relaxing with the heat as far as feeling loose... I tighten them up pretty good and never have a problem removing them... I only do about 40 a month though. Maybe the lube tech is just weak.
I know that a lot of times the little oil stain down the side of the filter is from when you are trying to spin the filter on while the oil is still seeping out of the housing on to the rim of the filter.

OilGuy