You are correct on the situation Grum. If you take say a Mobi1 or OEM and compare it to the latest Purolator or Bosch by looking at the end cap, you'll see the Purolator and Bosch are much shallower. On the FJR, it does have a hex on the threaded adapter, the issue was solved by machining ~.060" off the face of the hex to allow the filter to screw on a bit further.... note, most cars likely don't need as much depth? Dunno. In any case, Vulgar didn't say what filter he had the leak with..... but again, I'll check the depth on my engine when I change my filter.