Yesteday I had th ecoolant changed in my 98 Chevy Lumina. The mechanic called me over while and showed me a large amount of sludge that had bulit up in my radiator. They said I would need a new raidiator soon. I came home and checked online and found out for the first time about all the problems GM cars have been having with Dex Cool. There seems to be no consensus on exactly what to do from the point I am at now. The head gasket isn't leaking and the car is running cool and fine. My question is: What should I do now? Thanks.