: Dexcool



B1n2fra
09-08-12, 07:19 AM
I wanted to do a flush on my coolant system I wanted to know how much dexcool I should buy to get the job done.

Submariner409
09-08-12, 09:33 AM
Does your owner's manual list the cooling system capacity in quarts ? If so, you need enough DEX-COOL to make a 50/50 solution of coolant and distilled water (grocery store - distilled water, not spring water).

Kicker is, raw coolant comes in gallon jugs, so if your system holds 14 quarts you'll have 2 left over as spare. The stuff, kept in a capped jug, does not go bad when mixed.

I did not mention "pre-mix" coolant because it is so stupidly expensive compared to raw coolant and store-bought water.

EChas3
09-08-12, 04:06 PM
You don't mention the year of your STS or the coolent condition. Unless the system has been contaminated, you might not need a flush. Check the whole system for signs of leaks to make sure there's no water pump or hose on the brink of failure.

If you do flush & fill, do it right and you may trade the car before it's necessary again.

KRSTS
09-08-12, 07:03 PM
GM say DEXCOOL should be replaced every five years. No need to do it more often if the system is uncompromised.

mtflight
09-08-12, 07:07 PM
GM say DEXCOOL should be replaced every five years. No need to do it more often if the system is uncompromised.

Right except guess at what happens to the fwd north star owners that replaced it every five years/150,000 miles? Corroded head gaskets.

B1n2fra
09-08-12, 07:55 PM
No becsuse I was going to replace my water pump and I might as well flush since it's been leaking. My car is a 2007 awd northstar

KRSTS
09-08-12, 08:11 PM
Its due

mtflight
09-08-12, 08:28 PM
No need to flush if you use distilled water and coolant 50/50. Factory probably uses distilled or deionozed wwater. Tap water has the minerals and thus build up requiring flushing. Simply drain and refill.

B1n2fra
09-08-12, 09:13 PM
How many quarts for a drain and fill

EChas3
09-08-12, 10:09 PM
Check your manual. My 2006 AWD 1SG V8 says 12.5 quarts / 11.8 liters. I was in the same boat but had the dealer handle it under CPO.

Manuals are available in pdf's but paper ones still have value. If you have Navigation, you'll want the addendum.

malatu
09-09-12, 08:35 PM
Right except guess at what happens to the fwd north star owners that replaced it every five years/150,000 miles? Corroded head gaskets.

I believe the recipe for Dexcool has been modified since then.

mtflight
09-09-12, 08:52 PM
I believe the recipe for Dexcool has been modified since then.Was it the recipe or the gasket materials? Do you have any references? I'd like to know more.

I know OAT (organic acid technology) coolants sometimes have some additives that aren't friendly to some materials (nylon 66 and silicone rubber). I'm not sure what the recipe for dexcool is but I'd be interested to know more about said reformulation.

malatu
09-10-12, 12:21 PM
I dealt with intake manifold gasket failure on a GM motor 6 or so odd years ago. I did a lot of reading and you make a good point. Now that you ask the question, it very well may be a new recipe in making the gaskets, not Dexcool. Let me dig around and see what I can find. I know printed out quite a bit of information about this topic. I may still have it. I'll do some digging around.

malatu
09-10-12, 02:54 PM
Was it the recipe or the gasket materials? Do you have any references? I'd like to know more.

I know OAT (organic acid technology) coolants sometimes have some additives that aren't friendly to some materials (nylon 66 and silicone rubber). I'm not sure what the recipe for dexcool is but I'd be interested to know more about said reformulation.

OK, I spent way too much time revisiting this issue of Orange vs Green! There are a lot of forums that discuss this topic. Some posters suggest they'll never use Dexcool in their cars. Some use it until the warranty is up, then flush and refill with green or Prestone's compatible coolant. Other posters say it's fine to use and is better than green and would never use anything else.

I found numerous posts suggesting GM reformulated Dexcool so it would not eat away at gaskets. I couldn't find anything "official" or factual per se.

Another poster wrote he was a part of a class action suite where GM paid out money to owners of GM vehicles that had damaged gaskets from the use of dexcool.

I found numerous posts that stated GM started using different materials in their seals and gaskets that weren't impacted as greatly to Dexcool.

What's true and factual .... beats me.

mtflight
09-10-12, 04:25 PM
Thanks for taking the time to look. I think the way I'm interpreting is that currently Dex-Cool has Potassium 2-ethylhexanoate, and it is not compatible with Nylon 6,6 or silicone rubber. I have a feeling that some gaskets had more of the affected materials than others, thus failure was slower for some than for others and thus it was difficult to connect cause and effect. Definitely there's significantly more headgasket failures after DexCool in the Cadillac Northstar application (referring to the site's epidemiological poll).

curtc
09-10-12, 06:15 PM
The issue with the earlier N* HG failure had more to do with head bolts lifting rather than gaskets going bad...coarser threads/longer bolts were used in later models to correct the issue.

mtflight
09-10-12, 06:34 PM
The issue with the earlier N* HG failure had more to do with head bolts lifting rather than gaskets going bad...coarser threads/longer bolts were used in later models to correct the issue.

It may have appeared that way, due to galvanic corrosion. However, in order for this corrosion to take place, the electrolyte (coolant) has to be in the bolt hole, due to either casting porosity, or... a failing head gasket that has breached coolant into the bolt hole. If you look at these head bolt holes, they are very deep and can hold quite a bit of coolant. Definitely the galvanic corrosion that would start taking place would result in the head bolts lifting thereafter. I don't doubt at all that head bolts pull out with the aluminum threads attached. This looks bad, it looks like the problem. But it's just a clue.

The 93-96 models have the same head bolts and the same engine design--it's the same engine. No difference.

I believe the evidence is in the gasket... all the failed head gaskets I've seen and that have been posted on the forum here, look significantly corroded. These breaches are mostly in the areas exposed to the coolant--the water jacket. Some report that they are flaky and crumbling apart. Even those that have been religiously maintained. Another piece of evidence that we can't ignore is the epidemiological poll on the site--the clearest indicator is the change itself during the production year of 1996 (a lot of 1996 cars were built in 1995, not all had Dex-Cool).

http://i66.photobucket.com/albums/h267/mtflight/hgincidence.gif

The longer coarser threads and bolts with larger contact area would mask the problem by delaying failure, since it would take a lot longer for galvanic corrosion to cause the larger bolts to fail. Also, we don't know when the headgasket material was changed. Ford and GM (and other car manufacturers) changed gasket materials to become compatible with modern coolants. GM and Ford did so in response to failures (to date, Japanese manufacturers recommend their customers to stay away from 2-ethylhexanoate (http://bit.ly/O9OaLp) to be safe).

GM was a pioneer in the change to modern coolants, but unfortunately it came at a cost. If GM knew what was going on, they would've changed the gasket materials to be compatible with the new coolant. That's been corrected now. There's nothing inherently bad about Dex-Cool, it works, and that same organic acid technology is in use with either sodium or potassium 2-ethylhexanoate (http://bit.ly/O9OaLp) in most long-life coolants (Peak, Prestone, Havoline, etc).

The swap to Dex-Col was done before realizing some gaskets materials were incompatible, it was a very expensive accidental experiment. It took longer to show up on some cars than on others, due to the amount of silicone rubbers and nylon 6,6 present in the gaskets or materials.

curtc
09-10-12, 10:53 PM
Well, guess I went back to school today...Much thanks for the more informative details on the issue :thumbsup:...so, when did GM actually figure this out and change their gasket materials?

KRSTS
09-11-12, 08:30 AM
Well, guess I went back to school today...Much thanks for the more informative details on the issue :thumbsup:...so, when did GM actually figure this out and change their gasket materials?

Middle of last decade. I had a 2001 Silhouette that had the lower intake manifold gasket fail (very common) in about 2005. They replaced the gasket on my nickle since my warranty was out. I got about half of it back from a class action suit a couple of years ago.