Originally Posted by PhilSine
I've never heard that overtightening can bend the filter. Oil filters are pretty tough.
You hand tighten so that the filter can be more easily removed at the next change.
Over tightening can cause the base of the filter to contact the mounting point and distort it causing it to not seal. You also risk ripping/tearing the oil filter gasket. Most filters have a spec on the box or the filter its self on how far to turn it after the gasket makes contact(typically 1/4-1 turn). The idea is to tighten the filter to a point where the gasket has sufficient pressure to seal with out the base of the filter distorting or contacting the mounting point.
I would check:
1. look at the gasket mating surface on the block and see if it is smooth where the gasket sits, if not it will leak.
2. Make sure the threaded stud in the block is tight (it is common that they loosen up).
3. The infamous double gasket.
4. to see if you are getting oil trapped on the outer lip of the filter (outside the gasket between the gasket and the edge of the filter housing) when you install it.