Thank you for the replies and the information regarding the S1 gaskets. I've seen S1 gaskets that have collapsed, but it seems to be much less common than the S2 gaskets failing. After all the miles on my original set of gaskets, I'm very interested in seeing just how bad these gaskets are. Especially considering the crap I have already built up in just a couple thousand miles on cyl #1 spark plug since replacing all the plugs.
Regarding the ring around the overflow tank, I've always been led to believe that this is actually caused by leaking lower intake gaskets allowing oil into the coolant, which is transferred into the coolant tank and leads to the sludge buildup in the tank. I've seen this occur with Dex-cool as well as green coolant, which is why I feel that it is not so much a problem with Dex-cool as it is a problem with the vehicle it is used in.
I'm not saying that I support Dex-cool at all, whenever possible I have switched vehicles over to green, both my own vehicles and my customer'* vehicles.
'94 Bonneville SLE | 266K miles
CAI - K&N cone filter - polished intake runners - 140 amp alternator - 2.5" exhaust - Magnaflow hi-flow cat - Magnaflow dual outlet muffler - 106K on engine and transmission - Sold 1/14/07
94 VW Jetta - 151K - 2.0 - 5 speed - Ghetto black steelie wheel mod - Techtonics 2.25" cat-back system