There has been some question here about problems with Dexcool extended life coolant. I have gathered some info, not certainly scientific but relovant to those who are sitting on the fence. Case was my 98 Blazer, I ran it on a long trip with a leaky water pump unknown to me at the time. It started to run hot from lack of coolant and I topped it off with water to get home. New pump, and refilled using 50/50 mix and 2 wks later noticed a brown almost slimy residue in the recovery bottle and also in the radiator. Up until that point it was pefect in color and no sign of contamination. I used a chemical flush(GM addresses this in a TSB) and refilled. It has been fine since. I have made the rounds to dealers and talking to people with fleets of GM vehicles using Dexcool. This brown mud seems to occur when either the cooling system develops a problem and the coolant level gets very low, or when the ratio of coolant to water is changed. One guy I spoke with purposely ran a 20% Dexcool 80% water ratio and within 8 months developed enough crap to require removal of the radiator for a shop flush. So it seems that if the cooling system is in good order Dexcool offers significant benefit over conventional, however it seems to be less stable if and when a problem arises. I have run Dexcool in all my cars, motorcycles and this is the first problem I have had. Hope some of you find this helpful.

 

thanx for the info

 

yeah thats some good research you did! thanks.

 

What benefits does it have over conventional coolant?

 

They claim from 5-7 yrs, or up to 150k miles before system flush and refill is required as opposed to the 2yrs for conventional. It is also more environmentally safe as it is 100% biodegradeable. It is still toxic if ingested but since it is OAT or organic acid technology based it breaks down completely if released into the environment. It is also silicate free and supposedly prolongs water pump life. One guy I spoke with said because it claims to last so long people think they don't have to do regular top off and maintenance. Perhaps that's where some of the issues come from. Dealer service techs seem to be evenly split on it's benefits, kinda like motor oils. I have had good luck with it so far.

 

Another thought to ponder.......the mud seems to only happen in the S/T trucks/blazers. This comes from personal experience at the dealer and independent shops. I dont care for DexCool myself and I only run the green coolant.

Kyle

 

so basiclly ull want to run a 50/50 mix no matter what? i think ill be cleanin mine out i went with a 70% water 30% coolant mix for that hot *** summer we had and i heard water cooled faster so thats what it did.

 

You are right Tim, water is the cooling agent. One guy who was a rep for an oil company was nice enough to fax some questions I had about this. Seems they don't recommend much lower than 40% EG coolant, not less than 50% for DC. Two things happen according to them. With a lower concentration the anti-corrosion protection is not as good requireing more frequent changing, and the water consumption will increase since there is less coolant to act as a wetting agent. And also freeze point, obviously. Since OAT based coolant more easily breaks down proper ratio is more critical. Chemistry was never my strong point so I don't know much more than that. Makes sense, especially in my case. One thing that he also said was that the shelf life of EG was in some cases less than a year as opposed to up to 24mo. for DC. I have 5 vehicles with DC and have had only the one problem. Kyle brought up a point, I wonder why the 4.3's have more problems?

 

I have no clue why it happens so bad on the 4.3's, perhaps poor coolant flow capabilities...poor design in the radiator, I really don't know the reason, I am just a technician that fixes the problems. It could be related to cooler leaks....i.e. trans or oil cooler.

Kyle

 

I'm not sure how valid that argument is. I ran dexcool in my 87 iroc for a while at a 60:40 ratio water:coolant, and the only thing that happened is my heater core started to leak. I lost some coolant replacing some sensors and topped it off with water and it was fine. It was replaced with the green stuff when I got a new engine.