You said you have AN return lines, right? Some of the oil return fitting flanges sold by some companies for the TDO5 CHRA's are the same ones they use for GT30/35 CHRA's. The GT30/35 flanges feature bolt holes with larger openings than the OEM oil return flanges, so getting the lower oil pan flange to seal properly, can be problematic. Even with a new crush seal, oil will still leak past the seal, because of the larger diameter holes in the aftermarket return flanges. I had a chance to make some inserts for my flange when I worked at a machine shop a few months ago, that mostly fixed the problem I was having. I'm not sure if this is the case with all aftermarket oil return flanges, but the ones I have exhibit these problems.