Oil cooler leak

[m15256]

After driving (light use) the Volvo for a couple of years it developed a minor but annoying oil drip from behind the oil cooler. Nothing major and in hindsight I should have left it alone. I got 2 cooler seals from Tatanka as well as some extra water pipe seals and after moving those hoses and tubes in the way got the cooler off. The block side of the cooler has quite a distinct groove in it that looks like a square section ring like you see on an oil cooler should go there. But the seal from Sweden is an O ring and not particularly fat. Cleaned everything up, paying special attention to the surfaces for the water pipe seals and put the whole thing back together with a thin coating of Permetex 2 (non hardening but sticky stuff) on both water and oil seals. Left that to set up for a couple days. By the way getting the 2 water pipe clips back on up under the manifold was the worst part. Everything was fine. No water leaks which I was worried about and no oil leak. Well it slowly came back. I've now cranked down on the mounting nut on the pipe nipple as hard as I can which slowed down the oil leak. Lately it has gotten to the point where oil will flow out at a significant rate. Turn off the truck at the Post Office and when I come out there's an honest puddle. Engine running and the flow is dramatic. But today for instance it stopped almost entirely when I drove it twice and then the third time I started it the oil poured out again. So has anybody experienced the same thing? Can the oil cooler just be eliminated, screw the filter to the block and re-route the water pipe somehow to the block? Tatanka has always treated me right and I don't think they sent the wrong seal but I don't know what it is supposed to measure. Does anybody? Why does the leak start and stop now? No its not out of oil! Pressure relief ball hanging up in the pump? Getting under the manifold there to do this again is not something I'm looking forward to. If anybody has any suggestions I'd love to hear them. I've never subscribed to the practice of smearing silicone gasket goo everywhere. Maybe I should but when I started twisting wrenches there wasn't such a thing.
Thanks, Rick