[Jeff Higgins]

This whole IMS thing is a real conundrum. Probably the single most overblown "issue" in the history of Porsche. 20 years on, folks who are tuned into this issue (and not seeking to profit from it) seem to have arrived at some conclusions.

The only ones that seem to fail are the ones that were sealed and greased. Porsche later eliminated the seal, exposing the bearing to the engine oil mist floating about inside the cases. These never seem to fail. I'm not sure when the change was made. Some also suspect that on cars with sealed bearings, if driven enough and hard enough, the inner facing seal effectively fails and exposes the bearing just like the revised design.

The failure window appears to be around 30-40k miles. If it makes it through there, most agree it's going to be just fine.

The ones that failed seem to be almost universally on cars that sit a lot and make short trips. The grease just dries out, and the inner seal never "fails" enough to let crankcase oil mist past it. Many of these cars are never driven "hard enough", further contributing to the inner seal's longevity, grease drying out, and bearing failure.

Related to the above, the variable cam timing pistons, plungers, whatever they are called, also fail on cars not driven "hard enough". "Hard enough" means into the upper rev range, where the cam timing is changed by pressurized oil in these little cylinders. If that never happens, the same oil that it left Stuttgart (or Finland) with will still be in those little cylinders, now 20-some-odd years later, all caramelized and hard. There needs to be some flow through those things, so the oil in them gets renewed.

My car now has 174k miles on it. I just put the second new clutch in it. Never even considered the IMS bearing, which is still the original. Drive them properly, maintain them properly, and there will never be an issue.