Coolant Question on my 2001 GMC Sierra

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BuddTX

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Oct 15, 2005
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Location
Houston TX
Hello,

I would like to ask yall a question.

I have had no problems with my 2001 GMC Sierra since it was new (can't believe she is over 10 years old now and has 115K!)

Replaced Factory Dexcool twice in 10 years with distilled water and Dexcool.

However, had some PM (All hoses changed, among other things) by a good friend and his mechanics.

And as a favor, they filled up my radiator with "I don't know what".

Now they did fantastic work, but I want to get my coolant back to distilled water and coolant, maybe an additive.

Right now I am draining and adding distilled water every night, after driving it 45 min or so during the day.

I figure it will take me 6 or so "drain and fill" before I get mostly distilled water in there. (Knowing me, I will probably do 8-12, I over do everything!)

Oh, to give you a kind of idea what I do for my engine and tranny, I have used Mobil 1 in both the engine and transmission since the truck was new, and just switched to Royal Purple for both fluids.

So, my questions are:

1. Despite all the "deathcool" threads all over the net, dexcool has been good to me for 10+ years. I was thinking of re-filling it with Texaco Dexcool (after flushing with distilled water multiple times), UNLESS, there is a universal coolant that might even be better than Dexcool. Warantee is out, so "best for my truck" is what I am looking for. So, is there a better long term coolant over dexcool for my GMC Sierra?

2. Should I use a Radiator flush? I know I would have to flush it 6-10 more times after I add the flush, and there does not seem to be any rust.

2. Manual says 50/50 mixture of water/coolant, but I was thinking 70water/30coolant? I live in HOT HOUSTON, TX. Freezing is NEVER an issue here! I have a 4.8 V-8, and manual says that Cooling System Capacity is 13.4 quarts. Instead of going 50/50 mix (6.7 Quarts) I was thinking of going to only 1 gallon Dexcool (29.8%), to get a little better cooling. Note, I am NOT having any overheating problems now, but cooler is better, right? However, 100% distilled water is not good for long term care. Thoughts?

3. What about additives? Water Wetter, Purple Ice, Kool-it, I have heard them all called "snake oil" but all three are from reputable companies. I was suprised to see that LubeGuard Transmission additive is recommended here.

I think I know the answers, but I would like to get your opinions.

Here are my "answers" by the way.

You are not having any cooling issues, and do not have any rust coming out when you drain, so after you have flushed enough distilled water thru your truck (make sure you turn that heater on to get a good flush!), add 6.7 quarts of dexcool to your radiator system, and top it off with distilled water, and enjoy your truck for the next 10 years. Getting better cooling by reducing coolant, or adding additives, might give you slightly better temperatures, but may sacrifice long term reliabality. What good is 10-15 degrees if your water pump dies early, or if your radiator rusts.

(Man, I hate reading that answer! - I almost don't want to post this now!)

I still welcome your opinion, there are some really smart people here!

Thanks!
 
There's a reason they call it coolant. It helps cool the engine. 50/50 cools much better than the 70/30 you are thinking about. Coolant also adds boil-over protection. Here's the facts:

Boiling Point (sea level):
219° F at 40 percent concentration,
222° F at 50 percent,
225° F at 60 percent;

Also, coolant provides anti-corrosion protection.

So, 50/50 or 60/40 (coolant/water) is your best bet.
 
Last edited:
50-50 or 70-30 is a trade off. If you don't operate on the edge of subzero temps or egg frying temps you should be OK anywhere between. I like to use distilled water myself. But where I live the water is pretty good for cooling systems straight from the faucet. That is other than the chlorine they put in the water.

I normally run 50-50. But you could run 60-40 or whatever combo. I have run 70-30 before and never had problems. I normally run PG Propylene glycol coolant. I used to run Sierra PG coolant, but over the last 16 years have run Amsoil PG coolants. They reformulated the Amsoil PG about 7 or 8 years ago. It seems to do a good job.
I would not have a problem using Dexcool if it seems to be working for you. I have been working on cars for about 34 years and used to run regular cheaper coolant and change it every year or so. I never have had any problems doing that.

Though I think the newer coolants run longer with better corrosion protection.
 
Budd,

I own a Silverado with the same engine. Here is what I believe to be best for it. G-05 if one can get over putting what goes in Ford and Mercedes cars into their GM. Second choice would be Toyota coolant with the caution that no one top-off with similar color Dex-Cool and ruin a $300 water pump in short order. These are 100K mile coolants but I believe in 2yr/30K mile service. Coolant is almost as important as oil but it is negleted like brake fluid on many vehicles.
 
Originally Posted By: OldCowboy
There's a reason they call it coolant. It helps cool the engine. 50/50 cools much better than the 70/30 you are thinking about. Coolant also adds boil-over protection. Here's the facts:

Boiling Point (sea level):
219° F at 40 percent concentration,
222° F at 50 percent,
225° F at 60 percent;

Also, coolant provides anti-corrosion protection.

So, 50/50 or 60/40 (coolant/water) is your best bet.


I think he meant 30/70 (antifreeze/water), but I agree that a 50% mix is best.

Originally Posted By: 229
Budd,

I own a Silverado with the same engine. Here is what I believe to be best for it. G-05 if one can get over putting what goes in Ford and Mercedes cars into their GM. Second choice would be Toyota coolant with the caution that no one top-off with similar color Dex-Cool and ruin a $300 water pump in short order. These are 100K mile coolants but I believe in 2yr/30K mile service. Coolant is almost as important as oil but it is negleted like brake fluid on many vehicles.


I definitely agree with the last line of your post.



O/P, IMO run any of the long life formulations out there that aren't an all makes/all models type. GO5, Dex, or Asian Mix are all great formulations that will serve you well, but to answer your questions:


1) See above.

2) Unless you see sign of deposits in the engine (not including the reservoir), I'd say it's not needed.

3)I'm not a big fan of additives, except for special cases. IMO under normal circumstances, if you use a quality product, then you simply need to change it at or before it's specified interval and you'll be fine.


At any rate, I'd say you need to get that plain water out of there ASAP and get a 50% mix in there. If you want to flush with water that's fine, but don't leave water in for any longer than it takes to get the old stuff out.
 
Thanks for all the replies!

I do not know why I am obsessed over this! I just want to put the best stuff in there, and I keep thinking that there might be something better, but on the other hand, Dexcool worked perfectly for me for almost 11 years now, if I put Texaco-Havoline Dexcool back in there, and change it out every 3-4 years, I am good for another 11 years!

On the other hand, I keep on thinking that there might be something better, I was toying with the idea of using Peak Global Lifetime or Peak Final Charge.

Any thoughts on that?

Thanks again!
 
While others may disagree, I feel that in your application, Dexcool is well suited and very hard to beat. Keep it clean and it's additive package strong by doing your drain/fills every 3-4 years and you'll be golden.

When people have troubles with Dex, it's often because it's being used in a unsuitable application or in a poorly maintained system.
 
If I was having good luck with it I would probably stay with it. I know I have had good luck and known that I should stay with a product that is working well over the years. But I'm always looking for something better.

Sometimes it works out, but sometimes it doesn't.

You have to decide if you can live with the results it you have problems after switching.....
 
Having had to change out two intake manifold gaskets ('97 C2500 Silverado w/5.7 and '01 Alero w/3.4), I'm a Dexcool hater in those applications. That being said, it's all I use in my LS1 (5.7) and LQ4 (6.0) engines. If it is in an engine with a dry intake manifold, and is properly maintained (you don't have a problem here) it's hard to beat.
 
"Word on the street" (actually the internet!) is that Dexcool was reformulated somtime ago, maybe 2005 or so?

I have no proof, does anyone have any solid information about Dexcool being reformulated by GM?
 
As far as I can tell the spec is identical from day one with no changes.

Eric said it well: In a properly maintained system it's a hard coolant to beat.
 
Pete I got this info from from Chevron that the formula has not changed......The formulation might have changed due to different suppliers,different material and different manufacturing processes and that is what GM is stating to avoid Class action status....."GM: several formulations of DEX
GM argued that besides all the obvious differences between vehicles, engines, etc., that different formulations of DEX, different weather conditions, different uses for the vehicles negate any possible “Class.” And, that variations might have been made in the manufacturing or assembly processes at the factories"
 
No doubt that GM presented its argument in an attempt to avoid class status and that the article is vague on exactly what GM argued. Only a reading of the filing itself could answer that and it doesn't appear to be readily available. Different suppliers would explain different formulations, although the variations in the manufacturing and assembly process wouldn't.
 
Thank you to everyone who gave me advice, both here and on other posts.

So here is what I did:

After flushing the radiator at least 8 times with distilled water, (and opening up the heater valve each time), I drained the radiator once more, added a little over 6 Quarts of Peak Final Charge , then topped off with distilled water. As the total coolant capacity is 13.4 Qts, I think I am pretty much at a 50/50 mixture. (I might add 4-5 oz more!)

I had trouble finding Peak Global Lifetime (PGL), but I think I would have gone with Peak Final Charge, even if I had a choice. I special ordered the Peak Final Charge from O'Riley Auto Parts near my house, and it took them 2 days to get it in house.

I resisted the urge to add Redline Water Wetter (WW), or Royal Purple Purple Ice (PI). I figured, why mess with good chemestry? I am hoping for 10 more years of "still feels new" driving, so this is for the long term, so I did not want to (potentially) mess up the chemestry for a few degrees.

I called the Peak Tech Support, and he said that normally he would recommend PGL over Final Charge, but after telling him that I flushed out my system at least 8 times with distilled water, he then said Final Charge might be a better choice.

He also said that they have tested WW and PI with their coolants, and said that they do sometimes work, but the main reason for testing them was to see if there was any compatability issues, and he said that they did not find any compatability issues with products like that.

Why did I choose Peak Final Charge vs PGL? Well, talking to the Peak Tech, I felt that there seemed to be "more good stuff" in the Final Charge.

I will probably change it out, every 2-3 years or so.

Thanks again!
 
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