It's both, and it's way higher than 10% if the car is tracked.

2.5L's are the worst, since they are the original design, with early production hiccups, and has the thinnest cylinder walls, but later 3.2s and 3.6s still fail at a high rate. IMS is not the only weak point.

It really depends how the car is used. (DD vs. track car with little street use.) Of the Boxsters / 996s that are heavily tracked in the region, I can count a long list who have had catastrophic engine failure (probably 30-40%, including mine), so this is not just internet anecdote.

On the plus-side, they are so easily replaceable, and cost not much more than an air-cooled rebuild (and motors last around as long).

I don't think we got an answer to the previous question which I will reiterate and that is how many Dorki's (not general population because clearly we are not a part of that or you read it somewhere, blah blah) or even friend of a Dorki (assumption again) has had their 996/986 grenade due to an IMS failure?

Follow up question. Who has replaced their IMS, how long ago and with what product.

Follow follow up, when the IMS was removed was it 'worn'?

when i bought my 2000 boxster 15 months ago it had 50K miles and needed a clutch. so i had the IMS bearing replaced with the LN retrofit along with the clutch. oil was clean at the time but the seal was beginning to weep so would have failed eventually. still has original motor and no worries driving it.

last summer my '99 996 needed a clutch at 70k miles so had the IMS bearing retrofitted along with the clutch replacement. original motor and the oil filter had always been clean to that point. turns out the bearing was still perfect so doing the retrofit at the time was not necessary.

but, the peace of mind is well worth it! for the previous year-and-a-half i had been hesitant to drive the 996 any distance, had been always reading the filter folds and waiting for disaster to strike. the car ended up sitting for extended periods because it wasn't fun to drive anymore. needlessly so it turns out. now i drive the 996 every day. everywhere. long distance, short distance. and never a worry.

though with spring here again i'll probably start driving the boxster everyday, top down, and no worries.

conclusion: well worth it to do the retrofit.

As long as the motor isn't the 2005 and later motor, which can't take the retrofit w/o a tear down, I'd do it in a heart beat. Keeping a very close eye on the filter, doing oil changes atleast every 5k and regular driving are key as well.

Instead of replacing the IMS I bought an extended warranty on my car. Being that it only had 11k miles on it a 5yr/60000 mile $2.7K warranty made more sense than doing a $6K+ IMS replacement. The warranty has already replaced the alternator, a window motor, the a/c control unit, and a seat switch. Money well spent.

When my 996 needed a clutch Charlie inspected the IMS and said it was perfect. The car had 76k on it . I decided not to do the upgrade since the car was being sold soon after.

My concern is that there is very little long term data on the supposed upgraded bearings. I think when we see a lot of cars log a lot of miles with the LN bearing and not fail the piece of mind will finally be there for these motors.

Is that the going rate these days?

Did mine on the boxster when I bought it three months ago, with 59K miles. Needed a clutch anyway, so it was an obvious WYIT. Couldn't really tell if it was weeping, since the RMS was weeping a little too, but the old bearing seemed perfect when I popped it out. I used the LN retrofit.

The way I look at it, it is cheap insurance for ~$600.

That was the quote from Porsche of Arlington.

Ouch. I was lined up to do one of these and it fell through. Havent been inside a m96 yet but it doesnt look any more complicated than a clutch job and a t-belt on a 'normal' car. Appears completely DIY able if you have the time and a few of the special tools.