Take it from someone that found out the hard way. Get is checked by someone ASAP. I blew and engine a few years ago and upon INTERNET investigation I believe it was from the Dexcool problem.
What happened to me is that we purchased our 98 Silhouette van used in 2002. My wife was taking my daughter to school and the van just died. It was towed to the dealer where they said the engine had seized and $3700 and a new engine later we got it back but the sludge was still in the reservoir. I flushed out the cooling system myself and it was quite a job. The radiator and whole system were really gunked up. The dealer never admitted the blown engine was due to the Dexcool (we all here know it was).
Honestly, I hope you have better luck with yours than I have. This vehicle has been nothing but a lemon and money pit for me. Even now the stupid van is in the shop getting the tranny ($1800) fixed and also it has a leaky intake manifold gasket.
