cheap fix to leaking oil cooler
I have a 2004 Titan and had a leak on the block side of the oil cooler. I was also told that they do not sell the o ring separate from the cooler and it would cost $400 for the part and $100 for the labor. My dad and I came up with a solution that seems to work very well. When you change the oil again remove the ring from the used oil filter. Remove both of the hoses from the oil cooler (make sure to have something handy to plug both hoses, or you will be bathed in anti-freeze). Remove the oil cooler (as noted in a previous post, using a 22mm or 24 mm). Remove the ring (red/orange) from the back of the cooler and replace it with the ring that you removed from the used oil filter. I found that the oil filter ring has the same inside diameter as the cooler's ring, but the filter's ring is about 30% thicker. Also, the ring from the filter has a smaller outside diameter, so there is room for the thicker ring to expand when compressed. This seems to have stopped the leak, I paid no extra money for the part, and it only took about 10 minutes to get the cooler off and back on again. Hope this works out for you as well as it did for me. I still can't believe that it worked. Guess I'll have to change my pseudo last name of Murphy for a few days!