Don Terrill’s Speed-Talk

Hate to ask this kind of question in "engine tech" but-

Just did a coolant flush on the ol 2002 Chevy 2500HD with a LQ4 (6.0) engine and everything internally and the radiator hoses ect looked spotless. I had thought about switching to a G05 coolant or the old green stuff, but I saw zero corrosion and decided to stick with the DexCool that was in there. I had 3 full 5 gallon buckets of what came out of the truck and saw no rust scale or anything else, so I figured "stick with what works".

Whats the deal with all this internet chatter about Dexcool being garbage? My truck has 155K on it and the cooling system looks spotless and my heater core is fine. All the lines are original and even the plastic "reservoir" jug on the side looks good. Am I missing something or what?

Nope, if it ain't broke don't fix it.

One reason I have seen for wanting to switch is corroded rad cores fords are the worst but the coolant is not the cause.

When most system failures are repaired the coolant is blamed but if you remember to check where the rad rotted out you will see the inlet and outlet corners of the rad is rotted but the real reason is the core has lost it's ground to the body.

Seen a new rad put in an explorer and electrolysis killed it within 1 yr of use.
I put in a new core and replaced the ground strap and well thats been 9yrs now. That made a believer out of the rad shop that did the original replacement.

The wifes 02 GTP was originally filled with Dex-Cool.. One day the "low coolent" light came on.. But the coolent level was fine.. So I changed the sensor..

When I pulled the sensor out it was cover in a kind of jell looking substance.. With the new sensor in, and about 2 months later.. I got another low coolent light..

Around this same time I recieved a notice saying that I was part of a "class action law suite" in regarded to damages done by Dex-Cool.. And that I should document any charges I accrued from cooling system repairs..

If I had taken the wifes car to the dealer, and told them to find out why the light is on.. And they then charged me 400 dollar to repair it.. I might have went for that class action stuff.. Instead I flushed the system out.. Took the level sensor out and cleaned it off.. And refilled the system with Prestone "any-color" compatable anti freeze.. And I havn't had a problem since..

BTW.. Her car had about 70K miles on it when this all happen..

Dexcool = Very bad??? I have "heard everything" left in too long, grounds not attached, didn't get hot enough, orange, only Chevy uses it. I could go on but personally never seen the gelling and all the others when the stuff was serviced when it was due. Water is the most corrosive part of the coolant system from what I have seen.

"When I pulled the sensor out it was cover in a kind of jell looking substance"

I had the same problem with my Tahoe. However it had more of sand texture to it. I had to completely flush the system and I then switched over to the green stuff. No problems after the switch.

"supposed-ly" its the crap in the H2O not so much the antifreeze. Couple of jugs of distilled water(about1$ each)will clear up(no pun) the rusting/crapola problem. Like the other fellow sez....If you leave anything in there too long it goofs up stuff!
6sally6

I have heard that DexCool is "corrosive to plastics" which, as far as I know the only plastic in the system is the side tanks of the radiator, the connector elbows on the heater lines and heater core connections BUT- they all looked good so I figured I would just put in new DexCool and leave it alone.

I did remove the thermostat, completely flush out the system with a garden hose, poured in prestone "cleaner", ran it for a hour, drove 30 minutes of that, drained all that out, let it sit for a hour empty to cool down, then ran the garden hose through the radiator (disconnected from engine) then did the same with the engine with the t-stat out and made sure all the fluid that came out was collected. The buckets that had the most orange to them, I took to O'Reilly's. The buckets that looked like mostly water got the job of watering the backyard. (I have no pets)

As for the water, I've heard de-mineralized but our tap water here is very soft, so I figured it wouldn't be a problem. Plus, I practice agressive preventative maintenance so I won't wait 5 years/150K to do it again. The water pump on the truck is original, and I thought about replacing it, but hey- if its not broke, don't fix it. I just try to make sure I don't get a phone call from the wife bitching about being stranded somewhere in the car or truck.

The shops in this area suggest it gets drained out by 100K miles or problems happen, mostly plugged heater cores. I've seen the crustations inside radiators and heater cores and it's nasty. Never have any problems with the old green antifreeze even with tap water.

My 2000 silverado with a 5.3 and 90,000 miles had the heater core plug a couple years ago in the middle of winter. I slid the hoses off and blew air into the outlet, some brown sludge came out. This got me through winter and the following spring I flushed the system with a Prestone kit and refilled with the Prestone any color compatible antifreeze. The Dexcool I removed was nasty, I won't use it again.

Awful crap! Dexcool will cause severe corrosion in the cooling system and turn into some sort of coffee ground looking stuff in the radiator tank. It's REALLY difficult to get the system flushed out after all of this happens and we've found that the best approach is to flush, add a water filter to a heater hose line and fill with regular green ethylene glycol coolant.

nothing wrong with dexcool other than i think gm's 150k change interval is a little extreme. flush it sooner like you would green stuff and no problems. my car has almost 300k on it and i've flushed it 3 times. never had a plugged heater core, radiator or low coolant light. i think dexcool got a bad rap because it came out at about the same time gm started putting those famous plastic intake gaskets in!

Dont use demin or distilled water. It is mineral deficient and ''looks'' to replenish itself through corrosion.I work in a power station that uses demin water. The trucks that turn well water into demin water are fabbed from stainless for this reason...remember some older trucks that has some carbon steel construction. They were heavily corroded.That company stopped the use of carbon steel.

My brother and 2 other people i know had trouble with it.
I agree with the change interval being way too long. Another point is most people add non dexcool coolant to a dexcool filled system to top it off and this is what creates the jelling problem.

You can't mix and match even if the jug at autozone says "all types/all brands"

I have fast lube as part of our auto biz and see a ton of coolant systems. There was at least one class action lawsuit(which I think has been settled). IME, there is a problem with old or contaminated Dexcool causing corrosion and/or turning to 'jelly'.
Change it at 100k or 5yrs, whichever comes first, and it's okay if the cooling system is otherwise in good shape.