I came out to my car friday morning and started it went back in the house to let it warm up (9 deg) when I came out there was oil all over the ground. Not just a little oil about 4 quarts, and the valves were clattering of course. I shut the engine down imediately and opened the hoodit was not obvious as to where the leak came from so I few quarts in and started it. Oil sprayed out from above the oil cooler, I droped the oil cooler and found the o-ring that seals the oil cooler to the bracket to be split. I went to remove the o-ring and it literaly cracked and crumbled into pieces. Do yourself a favor r and r this o-ring if you have over 100,000 on your car, it only takes about a half hour. I am glad it happened that day because the day before I was traveling 100 miles at about 80 mph the whole way, think about what could have happend if i dumped my oil then!

 

I run Mobil 1 10W-40 High Mileage Oil. I think theyput seal conditioner
in it.

 

My car just hit 100,000 and the oil cooler, lines and rings were just replaced as they needed it. I dont know how common of an issue this is (I am definitely new around here), but sounds like something you should check out with you do the 90,000 miles tune.