Bill, with respect, weren't you meaning the M096 engines that are notorious for RMS seals leaking....lots of GT3's over here in the UK (of all generations) a lot of owners of which hang out on PistonHeads.

Whilst there have been a few cases of RMS seal probs on the 997.x GT3's, I never heard of one on the 996 gen (and had one myself for 3.5yrs, with no sign of weeping)....PistonHeads being PistonHeads, it would've been declared an epidemic within 30secs (!) had more than 1 car exhibited the problem.

Again, never heard of any 996/997Turbo owners complaining of RMS probs either, all of which use what folk over here refer to as the "Mezger" engine to distinguish it from the "cooking" models.

I'm a mechanical engineer too and I understand what you are saying (and it all sounds quite tech-ie - although you are talking about aluminum), but I think you will find the information on TI is readily available and requires no speculation.

There are numerous and persistent complaints about 996/997 GT3 & turbo rear main leaks, A quick search in the GT# forum over on Rennlist returns 59 separate threads about this issue.

I think Spenny must be thinking.."those americans blokes don't know how to properly drive their cars" hehehe

? Nah not at all, I don't subscribe to that cliched nonsense

I would say that you guys weren't fortunate enough to get the 996.1 GT3 or the 996.2GT3RS over there....in my experience of PPI'ing numerous GT3's when purchasing, hanging around 911uk and PistonHeads, plus driving other 996 GT3's and socialising with other owners over the 4 or so years I was involved with "GT3's" (a very close community in the UK), I never once heard anyone mention RMS weeps on the 996 variants; I do (did) acknowledge there were a few people mentioning 997.xGT3 RMS issues - generally taken care of by the OPC's....but again, I wouldn't put it in the epidemic category. 996 and 997 Carreras? Well, that's a different matter entirely!! :D Literally hundreds of threads posted (it became a very tiresome topic), and that's just the enthusiastic owners that frequent fora like this...shudder to think how many actual (unreported) problems there were with the less enthusiastic owners.

Engine seals
 

There is no reason why well designed modern oil seals should not be leak-free.
RMS are normally the problem seal mainly due to the larger diameter & continuous high surface speed especially in racing engines.
Our standard PLS Seal technologies are good for at least 50% vacuum & we have special designs for use at >75% vacuum.
These are all race-proven seal designs not concepts.http://forums.pelicanparts.com/uploa...1333791151.jpg

The GT3 not only has the two scavenge pumps (coaxial in normal pump location) in the crankcase it has one for each cam box as well for a total of four pumps, so the vacuum that can be created is greater than the air cooled system can.

There is a one way valve in the breather circuit to allow this vacuum to be captured.

The problem with the RMS is that the seal flap is designed as the usual system where more oil pressure = more sealing pressure at the flap. But the back of the flap is exposed to the residual crankcase vacuum after engine shut down and there is no countering oil pressure to seal the flap. Thus vacuum tends to lift the seal flap (even though there is the circular spring holding it down) and since there is quite a head of hydrostatic oil pressure beginning at the oil filter on top of the engine down to the seal not seen in the air cooled versions, oil tends to "burp" past the seal after shut down as crankcase vacuum equilibrates with atmospheric pressure.

Porsche initially plugged the back of the seal to protect it from vacuum and now I think the latest iteration of the seal is redesigned so that both oil pressure and vacuum promote seal pressure by flipping the seal around.