Going to flush my coolant on my 99 Eldorado. Whats the Best/Correct coolant to use in it? The Dexcool or the Prestone green? I know its 50/50 also but can I do a bit more coolant (60/40) for the Wisconsin winter without harming anything? thanks, Dan

 

Dexcool should be ok use distilled water to mix with it. You can use green but coolant change is every 24 month. Early dexcool would break down when cooling system was low, turning to sludge.

 

I guess I'll use the Dexcool. I do keep pretty close tabs on my vehicles fluid levels and oil changes. everyone says these Northstars are tempermental so i will keep a very close eye on things.