I've used fram filters for over 10 years now, and never had one single leak.

Perhaps those doing the oil changes are forgeting to coat the new filter gasket with some oil before they screw it on.
On a different note, I've been brainstorming ways to modify the deflector shield so I can change the oil, in a clean manner, without removing it. My GF's Corolla had a similar problem. I was able to cut the plastic shield under her car with my dremmel. Oil changes are a breeze now. Of course with the Z it's a bit different, considering the deflector actually serves a purpose. I'd hate to compromise the intergrity of why the panel is there or even cut an open hole in it, allowing dirty street water to splash up and dirty my immaculate engine bay.
Any thoughts?