DExCool- How long to change?

[Reg Saretsky]

I have had the Dexcool in my 99 malibu changed twice- once on a dealer gasket warranty repair,& again at 95,000 km. I am now at 2 years & 40,000 km since the last change.

Should it be changed more frequently than the 5 year 160,000 km dealer reccomendation? any thoughts?
thanks
Reg

[Polishpat]

Even though DexCool says you can go 100000 miles/5 years without changibg it, I noticed that its common for DexCool to clump up and cause sludge inside of your reservoir. I made the mistake of waiting 5 years with my Malibu and I got a descent amount of sludge caught up in my lines, and when I got to flushing out the coolant system, it was the most horrific coolant I have ever seen........in fact I had to flush it out three times, to get absolutely everything out of it. Since then Ive decided that I will do the flush every two years, instead of having to go through that mess again.

~Pat

[bcopeland]

Personally, I got rid of Dexcool a long time ago - flushed it out. All I use now is the Green multi-purpose use. I noticed the Dexicool not only clumped up, but clogged up as well.

[Johnny R]

What is involved in flushing the cooling system. Does flushing mean more than just changing the coolant? Thanks for any replies.

[bcopeland]

The best method is to get a pro flush from a shop. Second best is to use the Prestone flush kit with the hose adapters etc. and the flush in the bottle. However, you can use any of several methods.

['97ventureowner]

I change the DexCool in my GM vehicles in the range of every 2 to 3 years and 30,000 to 35,000 miles. I treat it like the "old school" ethylene glycol based antifreeze in the recommended change frequencies. At the time of replacing the coolant , I also replace my radiator cap at the same time as there have been reports of some radiator caps failing and allowing air to enter your cooling system, causing the DexCool to have problems, amongst them, gelling. For the price of the coolant and radiator cap, I think it's a good investment to change it every couple of years.

[Polishpat]

Originally Posted by Johnny R

What is involved in flushing the cooling system. Does flushing mean more than just changing the coolant? Thanks for any replies.

Flushing out the system means changing 100% of the fluid, as oppose to draining the radiator and reservoir which isnt all of the fluid. The way this works is by disconnecting the upper radiator hose and hooking up the colland flush machine to one end and directing the other hand into an empty container. The machine will then start pumping new fluid through your coolant system, while forcing the old fluid out. A complete cleaning will take about 20-25 minutes but garuntees all of your fluid to be fresh afterwards. Costs about $50-$75 for regular coolant and about $100 for dex-cool, depending on the mechanic, but well worth the money

[stratford_boy]

Dexcool is horrible stuff, when I first got my malibu, I flushed that crap out right away. (Done too many headgasket jobs at work bacause of it.) Dexcool carries a voltage that eats away at headgaskets and other soft materials in the cooling system. GM states that once this voltage reaches a certain level, to change the coolant but most new vehicles exceed this right off the showroom floor. Green coolant is tried and true and if changed at recommended intervals will pose no problems!!!

Flushing:

You have to separate the 3 main cooling system pieces: engine block, heater core and rad. Then run water through each separate part until clean water runs out the other end. Then blow out with compressed air. Fill with new coolant then top off with water. (3.1 engines should have 7L pure coolant for 50/50 mix.) To drain the block, there is a pipe plug near the oil filter.