Earl's makes a dead soft aluminum replacement "Cap"
http://www.amstreetrod.com/169101ASR.php4that fits on the male nipple of the
oil cooler. Often times if the sealing surfaces are damaged this will restore them. Secondly, as previously mentioned different designs of hose ends seal differently internally. The best I have found in the Ear's line are the Swivel Seal line and are the ones that use a "cutter" instead of just compression,. I fought an Earl's compression design fitting for quite a while before trying the other. The cutter design eliminates a path for the
oil to weep through. It may appear as though the sealing surfaces are at fault when in actuality it is the hose leaking within the fitting.