I've only used the motorcraft seal. The sealant I used was some permatex form-a-gasket wiped around the original crankshaft seal surface, lightly on the inside of the sleeve and again lightly on the interior perimeter of the rear plate. I think it helps the sleeve slide on a bit easier, especially when trying to use that useless plastic installer tool for both the seal and sleeve together. I had much better luck after I duplicated the critical dimensions out of some aluminum bar stock. If you can't make the plastic installer work, you can install the sleeve first and then ever so carefully get the inner lip of the seal gently slipped over the sleeve then you can mostly normally knock the seal into it's home. Gotta be real careful not to stretch the seal lips much or they won't return to size, teflon is not very forgiving in that aspect.
