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Getting conflicting advice on anti-freeze

i was going to get my anti-freeze flushed and re-filled with new in my 98 tahoe and was told not to use the original stuff but instead use the green. i was told that the orange stuff will and does ruin the cooling system.

what do you guys think? thanks!

You will continue to get conflicting advice here as well. a lot of regulars here do not agree o which antifreeze is best, probably the only thing we do agree with is leaving the old stuff in too long is not going to be good.

First piece of conflict will be about the flush. Some are for flushing out the old stuff and some are not. My recommendation is that you never use any of those flush chemicals in your cooling system. They dissolve stuff, that is never going to be good. In my experience people have more problems with their cooling system right after using any of those chemical than at any other time.

A mechanical flush, that is opening all the drains, block and radiator and or removing the lower radiator hose and using a garden hose (or machine) to pump fresh water through the system does minimal harm, but it doesn’t do any real good either. A drain and refill is adequate. You should drain both the block and the radiator though.

Don’t use the green stuff. It has a short life in an engine that has a significant amount of aluminum. This might be a moot point however as I haven’t seen the green stuff for sale anywhere lately.

It is OK to use the orange stuff, Dexcool. Your system is designed for it. But you can also use any longlife universal antifreeze. These new antifreezes meet all manufacturers specs. Usually these new antifreezes are yellow or red in color. It doesn’t matter, just pick one, completely drain your old stuff out and refill with the new.

I do not flush, the few residuals left in the system will be less harmful than the potential minerals left from tap water. Its like an oil change, the little oil that remains trapped in the engine will not harm anything.

You also have to make another choice, premix or full strength. You don’t use the full strength at full strength, you have to mix it with water. If you buy the full strength, I recommend that you also use distilled water to mix with it. The premix uses a purified deionized water mixed with the antifreeze.

My preference is to buy full strength and mix it with distilled water at a 2:1 ratio antifreeze to water. It gives it better freeze and boilover protection and puts more anti corrosives in the system.

Keith is right. There is always conflicting advice. I agree completely with him except for using Dexcool. It’s the worst coolant ever put on the market. Use the yellow or red coolant and you will be fine.

Here’s my opinion about Dexcool. It’s fine if you replace it every 5 years, like you’re supposed to. If you leave it in too long, as almost everybody does, all bets are off.
I am also no fan of the chemical flush.
Are you fairly handy? If so, you could save a few bucks and drain and refill the system yourself. You could drain the radiator and the block. And then refill with a 50-50 mix. It’s not that big of a deal. The only worry is getting rid of the old junk.

The problem with Dexcool is if air gets into the cooling system the Dexcool reacts with the air and turns acidic. That’s because Dexcool is an Organic Acid Technology antifreeze. This then causes the Dexcool to start eating away at the metal components and gaskets. And if allowed to continue long enough you end up with a brown sludge in the cooling system.

When GM owners sued GM because their cooling systems were damaged from the Dexcool, GM’s defense was that the vehicle owners didn’t properly maintain their cooling systems and GM won the case.

I have people bring their GM vehicles to me as soon as they go out of warranty so I can replace the Dexcool with a universal antifreeze, because they don’t want to have to worry about possible damage to their cooling systems. They tell me, “Get that crap outta there!”.


@keith: The “green stuff” is for sale everywhere. I have seen no shortage of it. I think “Dexcool” is okay under two conditions:

-You change it on schedule, as db4690 mentioned, preferably ahead of schedule IMHO if you live in a climate with temperature extremes.

-You make sure your cooling system is kept full–Dexcool reacts with air in the cooling system to form a gooey mess.

Tester…oblivion…you both just helped my case. Why would anyone use Dexcool when so many things can happen to an engine that allows air in the cooling system? A leaking hose or a bad water pump seal can play havoc with an engine by allowing air into the cooling system. The resulting acidic, gooey mess will destroy your engine from the inside. Why have it in there in the first place when perfectly acceptable coolants are on the market?

I suggest that you only use a product recommended by the manufacturer of the car you will be using it in. Any other anti-freeze may not be suitable for your car.

I had a 2006 Chevrolet Uplander minivan. Before I sold the minivan to my son, I had the cooling system flushed with clear water and green antifreeze installed instead of the DexCool. That was in 2010. My son has driven the Uplander way past 100,000 miles and has had no cooling system problems. My independent shop recommended the green antifreeze over the Dexcool and their opinion agrees with Tester. My son has the antifreeze changed on a 3 year cycle.

I preferred to avoid any Dexcool issues and went with Peak Global. No regrets.

Yes, you will get conflicting answers on here but-----Use anything except DEXCOOL!

You still do not want to use the “green” stuff in any GM vehicle that specifies Dexcool. Almost all manufacturers specifically say not to use it. The “green” stuff uses silicates in them and if you read your owners manual, you will see that they recommend against using any antifreeze that has silicates or they will say to use a silicate free antifreeze.

Dexcool is actually pink, and while I personally don’t have a problem with it, the universal long life antifreezes are as good or better and usually a little less expensive, and I am very loyal to that hip pocket if you know what I mean. Although I do stick to the major brands like Peak, Prestone or Zerex. I pick the one that is on sale. The universal antifreeze comes in yellow, red and orange.

Just curious what others think about my coolant change procedure. I drain the radiator when the engine is cold, then refill it with plain water. Then I drive it a day or too, then repeat (again when the engine is cold). I only drain and add when the engine is cold. The old coolant mixes with the plain water as I drive. I do this a couple times. Then I figure most of the old coolant is gone, so I refill with 50-50. I have always used Prestone.

Caution: If you live in a cold climate, don’t try this in the winter. You can never use just plain water if there’s a possiblity of freezing temperatures. In a cold climate, you need antifreeze protection at all times.

If you do that you don’t have a 50/50 mix of water and antifreeze in the cooling system.

If the cooling system has straight water in it,. then when you add a 50/50 mix of coolant that’s diluted down by the straight water in the cooling system. So you could end up with a ratio of 80% water to 20% antifreeze.

You want to drain as much of the water out of the cooling system as possible. Then add straight antifreeze that equals one half of the cooling system capacity. Then fill the cooling system the rest of the way with water. You then end up with a 50/50 mix.


@GeorgeSanJose I suggest you drain when the coolant is hot. That way the thermostat has opened and everything is flowing nicely. If the block drains are easily accessible (not behind the starter or a motor mount), I crack them open as well.
My philosophy is: drain fluids at operating temperature, regardless of whether it’s motor oil, ATF, coolant, etc.
Then I create a 50-50 mixture and refill. I let the engine idle, checking the level frequently, until I have good heat coming out of the panel registers. Then I check the level once again, drive the car and make my final corrections after my road trip.

Yes you will get conflicting advice. When I had my radiator replaced due to an animal, I questioned the shop about putting Dexcool back in the car again. They assured me Dexcool was no problem anymore especially if air is not introduced into the system. I got the same info from the GM dealer a couple years ago. So I just went with Dexcool again and its been fine. I do watch to see if there is any evidence of it turning dark though.

Prestone sells an antifreeze that works instead of Dexcool. Says it right on it. No need for funny choices or even serious ones. It mixes with it too.

The advice that I most agree with, is that of @keith 's and @JosephEMeehan recommendations.

Unsolicited Testimonial.
Six Of My Cars Are GM Units. Two Are Antiques That I Run On The Originally Specified Green Coolant. The Other Four Cars Specify DexCool And That’s What I Use In Them.

GM specifies changing the coolant at 5 year / 150,000 miles intervals. I generally run it 5 years between changes. I never have had any cooling system or engine mechanical problems with them, over many years.

However, I do check all fluids (except transmission) on all the cars that I’ve got on the road, every week-end without fail. It takes just minutes. These cars all have easy to see through coolant reservoirs and I visually inspect coolant level and look for that nice clean pink color.

When it comes to my cars I use what the manufacturer specifies in them when it comes to fluids, filters, spark plugs, etcetera.

GM cars come with 5 year / 100,000 mile drive train warranty coverage. I wouldn’t want to jeopardize this generous warranty by using something else.

Besides, do you really think that if DexCool was somehow defective that they would keep specifying its use in their vehicles ? If you think that then please explain your theory to me.


Antifreeze Words Of Caution.

We all know that 195*F coolant can be dangerous, but . . .

. . . When handling Coolant that has been stored in a cold garage/shed in an area of cold winter climate, be extra careful.

Coolant that has been cooled to below freezing can frostbite flesh instantly if accidentally spilled.

Coolant stored below 0*F can frostbite flesh even faster than instantly. Flesh turns white on contact. Don’t ask me how I know. I’m OK, now.