I replaced my factory oil filter adapter gasket at roughly 150k miles and like clock work it has begun to leaking oil again at 310k. I'll be replacing it next week, but thinking about it, it would have been prudent to just replace it when I did my last coolant flush 3 yrs ago since I have to drain down the coolant to replace the gasket. So now I will add it to the list of preventative measures when doing a coolant flush. BTW, I did my last one 2 years ago (approx. 40k miles).

So now...

Average Life Span for Oil Filter Adapter Gasket