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Discussion Starter · #1 ·
I recently was on a long (3000+ mile) round trip to the midwest. While at my parent's house in a remote part of MI, I noticed that the coolant overflow reservoir was nearly empty. There was less than 1 inch of fluid at the bottom of the overflow tank. I had not checked this before, so it might very well be that we've been driving the vehicle like this for thousands of miles.

Anyway, the coolant level was nowhere near the "full cold" line, so I figured it was a good idea to top it off before starting the 1700 mile drive home.

Given that my parents live in the backwoods-middle-of-nowhere, I could not find official GM Dex Cool radiator fluid. Instead, I found an aftermarket brand that lists compatability with several modern manufacturers. It specifically says it's compatible with Dex Cool, both on the front and on the back label, where it lists all the manufacturer's specs that it works with.

I bought this, thinking I was all set to go. When I opened it, I was surprised to find it was the standard ethylene glycol green color rather than Dex Cool pink. After pondering my options, I went ahead and mixed it 50-50 with water and filled the reservoir to the "full cold" line. This probably took 2-3 cups of antifreeze + 2-3 cups of water, so not very much relative to the total cooling system capacity.

Now that I've had some days to think about this, I am wondering if I made a bad judgment.

Do you think it's ok, or should I drain it and put 100% GM Dex Cool in? Any possible warranty issues in the future?

btw, I don't know why the reservoir was low in the first place. It's been holding at that new full level since I topped it off. Maybe it was delivered that way, and I just now noticed it.

Thanks.
 

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"Compatible with Dex-Cool" is a statement that can mean many different things depending on the actual product and the specific claims. It does not neccessarily mean they are interchangable. There are other products that are fully interchangable and essentially the same product (almost all of them starting as Texaco affiliates) and as far as I know they are all pink. Compatible simply means that the product will not have negative physical consequences such as forming solids or acids and will function as an effective coolant when mixed with Dex-Cool however those fluids generally do not have the long life and chemical protection properties that are "features" (and I do say that with some skepticism) of Dex-Cool which means that the combined coolant should then (according to Texaco) be serviced at the intervals of conventional coolant. Usually the non-pink "compatible" fluids fall into that category but I certainly am not up to date on all the products on the market
 

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I would get the green out! Also, I have noticed multiple posts that the coolant in the reservoir runs low. It seems like this might be normal.
 

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Discussion Starter · #4 ·
So, you think that 1 - 2 cups of this green "Dex Cool compatible" fluid needs to come out right away?

I was at least hoping to let it sit in there for 10,000 or 20,000 miles (with the factory Dex Cool) and change it out a little earlier than the factory recommended interval (which, according to page 505 of the manual, is an amazingly long 150,000 miles!).

My understanding is that Dex Cool mainly gives you extended intervals between antifreeze changes. If this imposter stuff is at least compatible and doesn't cause solids to precipitate out, I should at least be able to go some reasonable interval before having to change it out.

Any oher opinions out there?

Thanks.
 

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xcskier said:
So, you think that 1 - 2 cups of this green "Dex Cool compatible" fluid needs to come out right away?

I was at least hoping to let it sit in there for 10,000 or 20,000 miles (with the factory Dex Cool) and change it out a little earlier than the factory recommended interval (which, according to page 505 of the manual, is an amazingly long 150,000 miles!).

My understanding is that Dex Cool mainly gives you extended intervals between antifreeze changes. If this imposter stuff is at least compatible and doesn't cause solids to precipitate out, I should at least be able to go some reasonable interval before having to change it out.
I believe that you are correct and in line with the opinion of the manufacturer of Dex Cool

http://www.havoline.com/products/na/antifreeze_01.html

Note, that they recommend it not be diluted more than 10% with other coolants. I would think your "couple of cups" is well below that, and leaving it for a while and changing it out at an interval more typical of conventional coolants would be appropriate. FWIW. If I were short a small amount, as you were, I would suggest topping up with just water and later topping with 100% Dex Cool if the situation called for a top up and the appropriate coolant weren't handy.
 

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Discussion Starter · #6 ·
Thanks for the excellent link; it had a great write-up.

I feel much more confident now in my decision.

I think I'm going to quit worrying about it, and go with the 150K/5 year interval.

I did consider just adding water to the reservoir, but was worried that might somehow backfire on me. (No idea what exactly I thought would happen...)

Next time I'll be smarter. For sure, I'll make a point to look at the reservoir BEFORE departing on a long trip, rather than in the middle of it.

Thanks again for all the input. I sure do find this site useful. It really is a good internet "community".

Have a great day.
 

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The link also states this: Compatible with conventional antifreeze. Dilution with conventional antifreeze will reduce extended life benefits.

Yes, you might be OK for a while, but with this statement in mind, I don't think I would wait the full length of time. It doesn't say how much you can add and still have the extended life benefits. There is lots of gossip about mixing Dexcool and conventional causes problems. There is a lot of stuff in coolant and color alone is not what determines compatibility. Some additives may not be compatible with our cooling system parts.

If it were me, I would change it out. It just isn't worth the risk.
 

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I may be wrong, but I believe that we have a "coolant level low" warning on our vehicles. If you didn't get this warning light, then there would have been no URGENT need to add any coolant or water regardless of what level is shown in the reservoir. Just top it off at your earliest convenience with the correct DEX COOL coolant/water mix. I know that my 2001 Grand Am GT had this warning light, so certainly the lambdas monitor coolant level.
 
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