Oil cooler adapters will leak when the adapter rotates with an oil filter change. If the two parts rotate, even the tiniest bit, the clamped rubber gasket will leak. Easy fix when installing it - Mock up your cooler adapter to the filter adapter and mark the orientation to get it right, then pull your oil filter adapter off the bike (three bolts and two o-rings), and install the cooler adapter onto filter adapter on the bench. Get the rubber gasket hot on top of a light bulb for a few minutes, get the threads surgicaly clean, and then torque the center bolt that holds the oil cooler adapter to the oil filter adapter real tight, upwards of 100 ft lbs using red locktite. Now you got it on there good and tight, lets keep if from rotating. From the back side drill two small holes 180 degrees apart on the outside edge. There's just enough room. Now tap two roll pins into the holes. Presto - the adapter ain't ever gonna rotate, and it won't leak. I also looked at the 5 threaded holes that hold the two cooler adapter halfs together and didn't like what I saw. Two or three of these little 8-24 (?) holes are blind. I drilled/tapped and helicoiled the holes before assembly. Keenserts would have worked just fine too I'm told. Then I replaced the supplied cap screws with grade 8 ones from the local hardware store. They were torqued significantly tighter (red locktite) than I would have dared to do as the MOCO supplied the adapter. This probably wasn't necessary, but peace of mind isn't easy to come by, and now the oil cooler adapter is as bullet proof as it can be."