[thom4782]

I don't think it's amazing at all that your car is running after 12 years with 70K miles. While there may be 20 failure modes, most are pretty rare so 95%+ of the M96 engines last a long, long time. So I'd stop worrying.

The probably of an IMSB failure is very low especially if you change oil more frequently than Porsche recommends. One can improve his or her odds by installing an LN Retrofit bearing when one replaces the clutch. Then the chances of a subsequent IMSB failure become vanishingly small. At worst, one might want to check the LN bearing at 50K miles use to see if it has any play or wear. My bet is that the Retrofit will last much longer than 50K miles.

Second, one might want to replace the chain pads and tensioners in high mileage cars especially if one sees pad debris in the oil filter or sump. Other than that, I'm not sure there is much one can do to guard against the other failure modes.

Hope my 2 cents helps put things perspective.