Just a thought...

Who were the first owners I wonder of the car which had the trouble? I wonder how they were broken in and if they followed the recommended maintenance schedules like we all do?

I'm guessing if you had all the information at hand, you might see a trend of cars that weren't well cared for early on, yet see OK upon first glance. And those are the ones most prone to the issues.

Seconded!!!!!! I did the retrofit, its cheap for piece of mind.;)

From what I have heard people say, it's more often the garage queens that have the issues. And they could get all their maintenance 'on schedule', but if you only drive it 2k miles/ year...

I will add to Lt. Dan's list. All were Dorki/PCAP/local that I know personally. It's hard to tell how many are directly IMS related, but it's only because replacing with a crate motor is cheaper than to open up the motor to diagnose for a fix. But suffice to say all motors suffered terminal failure.

1) My own (986S)
2) Carlos R. (996)
3) Paul A. (996)
4) Michael J. (986)
5) Ram N. (996)
6) John M. (986S)
7) I sold my spare motor to a shop in PA to replace their customer's blown engine

As I mentioned before, the list are of people involved in DE so (1) it's a remarkably high % of failure rate; (2) these are all very well maintained cars; but (3) these motors are all driven hard

Well there we go -- add'l data that seems to contradict the 'barely driven' car theory.

I installed the IMS Guardian earlier this month.
Pretty straightforward install.
Only hard part was running the cable through the firewall.
I took about half the interior to end up going through the plug that the shift cables go through.
System seems to work well - but hopefully i will never found out - just broke the 80K mile barrier last week on a trip to NJ.

So it appears; properly cared for, broken in properly or not, garage queen or not for piece of mind and further possible expense it is recommended. I am waiting for my service adviser to give me a WAG as to the expense for RMS, IMS and clutch.

From my conversations, I'd say garage queen is bad and DD is good. These engines really hate sitting. Best thing is the oil and changes. Remember the bearing is intended to be sealed. Never stays that way, so, keeping the area as clean as possible is the next step, that and constant lubrication. The longer the sit, the dryer it becomes and the poorer/dirtier the oil the more damage that can result. The reason for the upgrade is to improve your chances. Don't think of it as a permenant fix.

Although, this goes to most of us believing that all SCs will need head studs, then hearing about the 400k car with original studs.

I think sums it up pretty well. Somewhere here in the past couple of years, there was a posted link to an article/video which explained the IMS failure very well. IIRC the bottom line was the same Mark puts it. Regular use leads to longer engine life vs. sitting around.

The PCA tech inspection last month at SportsCar Shop, there was a 996 up on a lift. I asked the shop workers about it, and they said it was in for leaky RMS, leaking AOS, and rusted out mufflers.

Their diagnosis was that these had failed from lack of use, and that driving the car regularly keeps all the various oil seals from drying out, and keeps water from accumulating inside the mufflers and corroding them.

I can't remember if he mentioned anything about the IMS bearing, but either way, it seems clear that these cars should not sit for long periods - they're meant to be driven.