I had the same problem with my 96 855 Turbo. I would advise that you get a new o-ring for the line/oil cooler junction along with the basket clamp device for this union. I like to put a tie-wrap around this clamp because it makes me feel more secure. I believe there was a gasket on the oil line/engine block junction? I think it was a 10 mm bolt and with the right socket extensions and/or u-joint I don't recall any difficult issues with getting it off. Just be ready for a boat load of oil to drain out of the oil cooler. When you are done, be sure to check thoroughly for oil leaks as this can make a quick mess, not to mention-ruin your engine. Should only take an hour or so...