The problem that people experience with DexCool is in engines with cast iron heads (like the 4.3) when the systems run low.
Where silicated coolants "plated" the inner surfaces of the cooling system and passages in the block and heads and provided some level of corrosion protection when the surface would dry out due to low coolant levels. With DexCool, the surface is very well protected as long as it is wet with the coolant. When the system runs low on coolant, areas of the head will loose coolant and the inner surface of the coolant passage will almost instantly dry out due to the heat and haze over with red surface rust. Then along comes a slug of coolant and washes the rust off. The surface drys again, rusts and another slug of coolant comes along and washes the rust off.
The red sludge you describe with DexCool is simply rust. If the system runs low long enough it will accumulate enough rust to actually get muddy. Simple explaination. Just keep the system full and DexCool is great stuff. It just doesn't tolerate the system running low a well as some of the silicated coolants.
The problem compounded itself over time on some vehicles that were run in a chronic low state. The mud from the rust accumulation would build up in the pressure cap fitting and unseat the presure cap seal. so...the system would not pressurize and would overheat. Then all the rust and mud was discovered....ack...big surprise. It would have been easier to just check the coolant level occasionally...
Checking the coolant recovery bottle is a good way to do it for routine look sees but it is a good idea to pop the pressure cap off occasionally when the system is cold and check the radiator level, too. If the cap is malfunctioning, the wrong cap or if the hose to the coolant recovery bottle has a hole/crack/kink the radiator cannot pull coolant back into the system when it cools down and the level will steadily drop and will run low. so...once per month or so, check the radiator itself to make sure it is completely full to the brim as evidence that the cap is working correctly.
You should have absolutely no problems with DexCool. It is well tested and an excellent product if used correctly.
I personally always recommend the use of the GM coolant supplement pellets ( or the equivalent BarsLeaks products HDC ) to ensure against any internal coolant leaks into the oil. An engine like the 4.3 can leak coolant internally if a gasket starts to fail or something so the coolant supplement/sealer is good insurance against this. It is/was factory installed in that system and needs to be replenished over time and/or as the cooling system is refreshed. I would add 6 of the coolant supplement pellets to ensure a positive seal of the system. It causes no harm and will be perfectly benign unless there is a leak somewhere.
Where silicated coolants "plated" the inner surfaces of the cooling system and passages in the block and heads and provided some level of corrosion protection when the surface would dry out due to low coolant levels. With DexCool, the surface is very well protected as long as it is wet with the coolant. When the system runs low on coolant, areas of the head will loose coolant and the inner surface of the coolant passage will almost instantly dry out due to the heat and haze over with red surface rust. Then along comes a slug of coolant and washes the rust off. The surface drys again, rusts and another slug of coolant comes along and washes the rust off.
The red sludge you describe with DexCool is simply rust. If the system runs low long enough it will accumulate enough rust to actually get muddy. Simple explaination. Just keep the system full and DexCool is great stuff. It just doesn't tolerate the system running low a well as some of the silicated coolants.
The problem compounded itself over time on some vehicles that were run in a chronic low state. The mud from the rust accumulation would build up in the pressure cap fitting and unseat the presure cap seal. so...the system would not pressurize and would overheat. Then all the rust and mud was discovered....ack...big surprise. It would have been easier to just check the coolant level occasionally...
Checking the coolant recovery bottle is a good way to do it for routine look sees but it is a good idea to pop the pressure cap off occasionally when the system is cold and check the radiator level, too. If the cap is malfunctioning, the wrong cap or if the hose to the coolant recovery bottle has a hole/crack/kink the radiator cannot pull coolant back into the system when it cools down and the level will steadily drop and will run low. so...once per month or so, check the radiator itself to make sure it is completely full to the brim as evidence that the cap is working correctly.
You should have absolutely no problems with DexCool. It is well tested and an excellent product if used correctly.
I personally always recommend the use of the GM coolant supplement pellets ( or the equivalent BarsLeaks products HDC ) to ensure against any internal coolant leaks into the oil. An engine like the 4.3 can leak coolant internally if a gasket starts to fail or something so the coolant supplement/sealer is good insurance against this. It is/was factory installed in that system and needs to be replenished over time and/or as the cooling system is refreshed. I would add 6 of the coolant supplement pellets to ensure a positive seal of the system. It causes no harm and will be perfectly benign unless there is a leak somewhere.
