Dexcool.

Oct 27, 2004
3,000
4
I've just finsihed watching a video about Dexcool.

GM?s Jay Dankovich and Equilon Enterprises? (Texaco) Stede Granger directed a 2-year study of thousands of dexcool cooled vehicles. Their presentation is a 14-minute video that is now being circulated to technicians at GM dealers nationwide. In fact, if you REALLY want to see it you can buy the video for only $10 (plus S&H). Call MSX International of Auburn Hills, Michigan at 800-393-4831. Ask for the DEX-COOL video: ?Understanding Radiator Cap and Cooling System Contamination.? Part number: RADCAPK.

Let me brief you on some interesting (To me at least:)) points.

1. Keep the cooling system filled. In fact, fill the reservoir bottle to ?Hot? level when the system is cold. Problems arise when a system?s coolant level is not maintained. (Fleet vehicles receiving regular maintenance, and with reservoirs kept slightly above normal, do not show signs of contamination. This even applies to the specific ?problem? vehicles.)

2. The coolant problems found in this survey were caused by system contamination, and not due to the breakdown of DEX-COOL.

3. Check and keep the pressure cap clean and functioning. A contaminated and/or malfunctioning cap causes low coolant levels, which in turn causes overheating and a greater loss of coolant: the notorious vicious cycle. No matter what the vehicle, if the cooling system acts suspiciously, test the pressure cap.

4. On the ST vehicle models mentioned in the GM DEX-COOL video, you ?must? replace all suspect radiator caps, especially those with a Drop-Center design, with a Stant Model 10230 or 11230 (Spring-Center type).

5. Make sure that the coolant is at a 50-50 mix. Often, the flush water was not being removed from the engine block. Consequently, when a 50-50 mix is added to the system the resultant mixture could approach 30-70. Like any fluid that has been diluted beyond its recommended levels, the lowered level of inhibitors will not be able to protect the coolant system effectively. Low levels of inhibitors can cause pitting on aluminum surfaces and general corrosion of cooling system metals.A safe method of achieving a true 50-50 mix is to first determine the actual capacity of the system (use the owner?s manual). Then add 50% of ?that? amount of undiluted DEX-COOL (or any coolant), and top it off with water.

7. Mixing a ?green? coolant with DEX-COOL reduces the batch?s change interval to 2 years or 30,000 miles, but will otherwise cause no damage to the engine. In order to change back to DEX-COOL however, the cooling system must first be thoroughly drained and flushed.

8. Bacteria cannot live in a hot, Ethylene Glycol environment and is therefore not a threat to DEX-COOL.

9. While there have been intake gasket failures on CK Series, V8 powered vehicles for various reasons, DEX-COOL has never been found as a cause.

10. Use a refractometer to check the condition of DEX-COOL. Its inhibitor package is strong enough that if the batch still provides proper freeze protection, it is probably still providing proper corrosion protection as well.

11. DEX-COOL can handle the minerals in hard water better than silicated conventional chemistry coolants. Drinkable water is suitable for top off. This is news to me, of course. I would however, stay with distilled as its a more consistant product.

12. In ST Blazer applications where the radiator cap is mounted at an angle to the ground, the vehicle is more susceptible to radiator cap contamination and its related problems. The Stant 10230 is a wise choice for these vehicles.


Now, sure, most of this is GM related, But series 2 and other Rovers use Dexcool, and many people on here have GM products.
 

mbrummal

Well-known member
Jan 23, 2009
2,893
22
Willow Spring, NC
eh. I've been running 'the green stuff' for as long as I've had my truck. No problems whatsoever. Still no problems after overheating a few times...knock on wood...
 

KyleT

Well-known member
Mar 28, 2007
6,059
8
39
Fort Worth, TEXAS
LR says we are supposed to use distilled water. I think there is truth to that theory.

IIRC LR recommends dexcool in everything except the BMW 4.4L which takes blue G48. there is a bulletin about it somewhere...

Chris, is there a brand recommendation or is it pretty mmuch all the same?
 
Oct 27, 2004
3,000
4
KyleT said:
Chris, is there a brand recommendation or is it pretty mmuch all the same?

There are three basic types of ethylene glycol coolant.

1. Conventional/traditional

2. OAT organic additive (acid) technology

3. HOAT (Hbrid OAT with silicates)

They are all available in every color you can imagine.

HOAT are further divided into parially formulated (requires a supplement for diesel applications) and fully formulated can be used as is in diesel applications. The fully formulated can be substituted for partially formulated. The addition of silicates provides fast acting protection that OAT coolants lack and provide a barier that protects plastics from potential deplymerization of some plastics.

Fully formulated HOAT Examples: Zerex G-05, Chevron Custom Made, Texaco/Havoline Custom Made, Motorcraft Premium Gold, Mercedes Benz, Freightliner Purple long life, Mopar Long Life Orange, Mopar Long Life Gold/Amber, Peak CF-EXL, MTU Green.

Partially Formulated Examples: VW Blue, BMW Blue, Volvo Green, Zerex/Glysantin/BASF G-48 (Saab and others have used this also. If it's Blue and European OEM, It's G-48).

OAT comes in many varieties. The Japanese have high phosphate versions and a few molybdate versions. Molybdates improve water pump protection. European and American versions are phosphate free. GM and others that are "GM Dexcool approved" and some "one size fits all" versions use a specific 2-EH acid that some OEMs believe cause problems and are dead set against. European and American versions are usually phosphate-free. All are silicate free.

Toyota uses a couple of non 2-EH versions with molybdates for extra cavitation protection.

Peak Global is a non-2-EH version.

Most European red/pink coolants are Zerex/Glysantine/BASF G-30. VW/Audi/porsche, Jaguar and others use it and have used it.

GM/AC-Delco/Shell/Chevron/Texaco/Havoline is the 2-EH Dexcool stuff and Zerex/Gysantine G-34/Extreme Life 5/150 is the European Dexcool (Newer Saab etc) with molybdates.

Conventional coolants come in passenger car (ASTM D3306) partially formulated HD (accepts supplements for HD service) and fully formulated (Ready for HD service). All include silicates for fast acting protection against abrasives and water pump cavitation. Supplements to address HD cylinder liner cavitation include the SCA/DCA-2 nitrite stuff and the DCA-4 molybdate/nitrite stuff.

Silicates can cause problems in some cars Phosphates can cause problems in some cars 2-EH acids can cause problems in some cars Borates can cause problems in some cars Silicates are required in some cars 2-EH acids are required in some cars

Since Rover uses Wet sleeves, I would use a g-05 over dexcool. as its simply just a better product.
Make sure you use distilled water or all bets are off.

I would like to talk about mixing coolants.

In general, GM and coolant manufacturers all claim that mixing other coolants with Dexcool will not create any significant problems other than shortening the life of "long life" coolant to 24 months.

However there is much evidence to the contrary. All bets are off when mixing any two coolant formulas. This is true regardless of color.

Mixing Chrysler/G05 orange with orange Dexcool appears to cause plastic/nylon 66 http://home.comcast.net/~roadska/nylon66.pdf deterioration (even worse than Dexcool alone)

Mixing Japanese red coolants with European red coolants appears to have also caused problems.

Adding green coolant to Dexcool seems to also accelerate problems, but that statement begs the question: Which type of green coolant?

Today green coolant can be 1. Traditional high silicate American car coolant 2. Parially formulated HD low silicate coolant 3. Fully formulated HD low silicate coolant 4. Any of several other less common green coolants

Each of the above has a different additive formula that can react differently with Dexcool and other coolants.

Flush the cooling system extensively before changing coolants.

The carboxylates in Dexcool have been determined to cause polymerization of nylon 66 when left in use over 24 months. Nylon 66 is used throughout the cooling system including as a backing/support in many gaskets and seals. Mixing different organic acid coolants with Dexcool seems to accelerate this nylon 66 destruction, but I don't think adding an inorganic coolant to dexcool would do the same (but who knows?).


Use a Distilledwater unless you are sure that your water content is below:

100 ppm total hardness

50 ppm chlorides

40 ppm sulfates 250 ppm total disolved solids

If you use distilled water, buy it in 1 gallon containers and mix any unused portion with coolant as soon as reasonably possible. Distilled water absorbs CO2 from the air and forms acids.

If you want a true long life coolant, my choice is G05. G05 is the factory fill in Mercedes Benz, some chryslers, some Fords and some Volkswagons. It has been around long enough to have a good track record with many different materialsand conditions. Ford and M-B even use it in HD truck applications. It is available from several sources and in several colors.

Chrysler - orange Mercedes - clear Ford - Gold/yellow (Motorcraft Premium gold) Zerex - Gold/yellow

G05 seems to be good for at least 5 years/100,000 miles but the rest of your system isn't. Radiator caps, hoses, fittings, tees will all probably be outlived by the coolant.

If you choose long life, I think you should also go with a stainless steel "premium" thermostat (Stant has one), silicone premium hoses (Goodyear, Gates and Samcosport are good sources), or the new electrochemical resistant "Gates greenstripe" hoses, premium brass fitting and brass or soldered copper tees. If the freeze plugs are old, I'd replace them with brass too.

If you do all that and put in G05 you should be good for 5 years but you still better inspect it every year.

WaterWetter.

I don't know what it actually is. The bottle only says "contains alkaline materials." It comes in a diesel version and a gas engine version. Redline tells me that the diesel version contains less or no additives because it is expected that all diesels will be run with coolant mixes already containing additives; the gas version has additives (probably mostly or all for corrosion) because it may be used with water only or with a coolant mix. Of course, I bet they dont know how awesome I am, of they would tell me what this stuff is. ;) Racers use water only, because of coolant spill issues (antifreeze slippery) on the track and because water only has better heat transfer properties than an antifreeze mix. The Water Wetter provides maximum benefit of improved heat transfer with water only; but is still effective with any antifreeze mix. In the summer with no risk of freezing, I dont see a problem other then I'm concerned that it is likely to increase cavitation, but I might be overly cautous. Do an internet search on "black coolant" and you will find an OEM approved (but not GM approved) alternative formula that should also improve heat transfer. http://www.penray.com/images/99.014.pdf Heres one
 
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Blueboy

Well-known member
Apr 20, 2004
3,205
459
Back in the USA; Rockwood, PA
thx for the info Chris.

I'm always looking for ways to make sure the cooling system is at its best for Blueboy as it is one hot running engine with the way it is set-up.

best,

Jaime
 

jymmiejamz

Well-known member
Dec 5, 2004
6,008
361
35
Los Angeles, Ca
It is my personal opinion, based on no scientific evidence, that Dexcool is part of the reason for head gasket failures on DII's. If you have ever seen a failed head gasket on a DII then you have probably seen where the gasket material seems to have been eaten away on the outside of the cooling jackets. For this, reason I switched to the green stuff when I did the short block in my truck and I just change it every year. I'm not the only one at our dealership to do it either.


I'd also like to add that I think the Bosch plenum is part of the head gasket problem as well, because it allows too much heat build up in a relatively small engine bay.

Once again all of this is based on experience and speculation, not fact or scientific evidence.
 

knewsom

Well-known member
Jul 10, 2008
5,262
0
La Mancha, CA
Is this an issue limited to the D2? Or are late model D1's at risk also? I believe I'm currently running the green, but it was not I who last replaced the fluid, but my mechanic. Perhaps I should do a swap also.
 

jymmiejamz

Well-known member
Dec 5, 2004
6,008
361
35
Los Angeles, Ca
knewsom said:
Is this an issue limited to the D2? Or are late model D1's at risk also? I believe I'm currently running the green, but it was not I who last replaced the fluid, but my mechanic. Perhaps I should do a swap also.

It certainly won't hurt to change your fluid, it should be done yearly.
 
jymmiejamz said:
It certainly won't hurt to change your fluid, it should be done yearly.

Land over used to say every 24 months.

I've seen intake manifolds deteriorate to the point of replacement with good old green ethylene glycol coolant.

I find it curious that Land Rover indicates 24 month coolant flush intervals, but dos not provide a drain plug!