Changing out the Coolant

[Tony T.]

I was getting ready to change out the coolant in the wife's 99 GMC Jimmy. Coolant suppose to be good for 5 years or 150K miles which ever comes first. I was reading through the Owners Manual an it says to use DEX-COOL antifreeze with a 50/50 mixture of "clean-drinkable water". Did'nt say any thing about using deionized or distilled water that I can find. Now my 03 CTD says to use a ethylene glycol antifreeze coolant (HOAT) an use either deionized or distilled water with a 50% mixture. What gives, why would'nt the Jimmy require using the distilled or deionized water. Is there that much difference in the additives between coolants that one says use the garden hose an one says you must use this high quality H2O. I would bet if you carried your truck to the dealership for a coolant change they would use the trusty ole' garden hose for the flush out an mixture refill. Could you use one of those filters on a garden hose like you see while camping that some use at the campgrounds, that are suppose to remove mineral deposits an such in the water. What do you think most people use regular tap water or the distilled.

 

[Sojourner]

First of all, you don't want to use hard water ever, even to flush your coolant system. The minerals in hard water will begin to 'fall out' (precipitate out) at temperatures as low as 120 degrees F. You want to use as water that is as soft as possible.



I don't totally recall the conversation I had with the Royal Purple tech support guy when discussing their Purple Ice product, but he advised me against using de-ionized or distilled (also de-ionized) water - somthing to do with having an adverse effect on the interior surface of the radiator which would result in the loss of cooling capacity. He advised using "bottled spring water or bottled drinking water" in the mix with the antifreeze. I had told him I had used distilled water in the coolant system of my '01 and he told me to get it out ASAP and replace it with water which is not de-ionized.



I am unfamiliar with the '03 CTD coolant requirements, but it sounds to me like you might want to do some more research along these lines regarding the use of de-ionized/ionized water.

 

[rbattelle]

Hey Tony,



I'd be careful with the GM products and their Dex-Cool. Follow their recommendations exactly... if they say potable water is what to use, then do so.



Also, I recommend checking out www.bobistheoilguy.com for lots of good information in their cooling system forums!

 

[Tony T.]

Check out Bob

Thanks Ryan, I was familiar with Bob's site, but only really checked out the oil an fuel additives forums. There is some good info about coolants also.





Tony