Cadillac Repair: leaky oil cooler o-ring, caddy, radiator

Question
My 95 Caddy DeVille has a slow leaking oil cooler hose o-ring by the radiator(bottom hose, top hose to radiator is OK).  I've tried changing the oil cooler hose ($75 part), radiator (was getting old anyway), changed to a larger o-ring (11x2.5mm, original was 11x2.0mm).  Always torqued it to 15 ft/pounds. And it's still leaking.  What can I try?

Answer
Hi Charles, Changing to a larger o-ring might be your problem. If you got an o-ring with the wrong type rubber that could be it also. The caddy dealer should have the o-ring for this application and it will be the correct size. Remove the leaking end and make sure that there isn't anything still inside the rad fitting like a piece of the old o-ring and that the fitting isn't damaged/grooved. If all looks ok then install the correct o-ring and tighten it up and the leak should be gone. Hope that helps. Bill