Oil Cooler Failure

I just had an exciting occurance. After about 1:30 cross country I landed to drop off my brother. When I went to get back into the airplane I found a great deal of oil everywhere.

It turns out the oil cooler had failed. I think it must have happened in the last few minutes of flight. I still had 3 qts of oil left but had left northern Wisconsin with 9 qts on board.

How often does this oil cooler fail?