Cooling System

I have an '01 LS and just recently had a "no heat" problem. When I opened up the radiator cap I found what looked like rust/sludge. Took it to the mechanic who said GM's DEX-COOL anti-freeze turns into that after awhile. He flushed the entire system (1 week ago), and guess what....Still have the same problem. Now I think I will have to change all hoses and quite possibly a heater core...After doing some research, I found that this is a very common problem that can cause alot of damage. This is just an FYI post. Check you cooling systems if you have the orange DEX-COOL anti freeze.

Orange coolent should be changed every 5 years or this will happen.

Ok, butalso have an '03 Venture and guess what, it's startin to sludge up too. Me thinks DEX COOL is bad

03, 04, 05, 06, 07, count is 5 years.

Forget what GM says about changing Dex Cool every 5 years or 150,000 miles. It should be treated like the old green (ethylene glycol) coolant and changed out every 2 to 3 years and between 30,000 to 40,000 miles. At that tome it is a good idea to flush the cooling system as well. The problem generally is not with the Dex Cool but lack of proper maintenance to it. You should also check your radiator cap to make sure it is not leaking air into your cooling system as that has been shown to cause the coolant to sludge. Once a system has been neglected and sludging has occurred it is hard to get all of the old sludge out as it finds it's way into every part of the cooling system .

It doesnt hurt the car. If the radiator is low just ad some anti freeze or water

It doesnt hurt the car. If the radiator is low just ad some anti freeze or water
It can hurt the car though. If your cooling system is low on Dex Cool that means there is additional air taking up the space where additional coolant should be, and that air can cause the coolant to sludge up , causing all sorts of issues within the cooling system. Also don't just randomly add water or coolant. Unlike ethylene glycol, Dex Cool works best when it' mixed in a 50:50 ratio with distilled water.

I agree with this totally. I have not found this sludge in the dex cool coolant in 2000 silverado 120,000 and the 96 impala 55,000miles. only distilled water but I use a 65/ 45 water ratio 5yr complete r/r no flushing no running vehicle at all when replacing coolant..