You sure it is'nt leaking down the back side of the filter cover and is mimicking a leak in the ribbing of the upper oil pan. The ribbing... cast in the upper aluminum pan has finger sized squares and triangles cast in. Did you remember to put the o-ring in for the filter tower cap? Is it seated properly? As mentioned, there is'nt anything with a grommet in the place you've described. How is the lighting where you at? Could you shine around the filter tower with a flashlight...if you have'nt already?