Buying a new oil cooler o-ring for my 98 Mazda 626 2L where I live is extremely expensive, I'm not sure that even the dealer ship has the right part and I can't seem to find a part number anywhere. I ran across this post regarding changing the oil cooler gasket on a Mazda MX-6 which uses a similar o-ring type gasket:
But yes, using the gasket off a regular oil filter does seem to work fine.
Anyone ever heard of such a thing?