Dexcool Issues

[NTX5467]

After reading the post a while back on retrofitting Dexcool coolant into earlier vehicles and also reading the commentary by Patrick Bedard in the July, 2002 "Car and Driver" magazine, I did some research on the web tonight and determined that such a <BR>conversion might not be advised in some situations as there are some important side issues.<P>Key issue -- Dexcool was designed for new vehicles which never had any green antifreeze in them at all. This could also include an older vehicle with a freshly overhauled motor, new radiator, and a new heater core, but the issue of lead solder in the system might be another issue too.<P>The year that Dexcool was first put in new GM cars at the factory, it was used universally in all of their cars and trucks in North America except for the Pontiac LeMans (built in Korea). A Buick rep came by the dealership to advise the sales people and others about the "new for that year" features on new Buicks. I had a chance to discuss Dexcool with him between meetings.<P>That first year, GM had exclusive marketing rights to sell Dexcool (even though it was produced by Texaco or jointly developed with GM, whichever is the case I don't recall now) and then Texaco could sell it the next year. After that first year, others could sell the Dexcool formulation too.<P>Dexcool chemically coats the entire cooling system during the first 3000 miles of use. This is an anti-corrosion coating and allows the solution to be completely silicate free. If, in an "emergency" situation, some non-Dexcool coolant is added to the system, in order to maintain the 100,000 or 150,000 mile change interval, the system and the contaminated coolant should be completely flushed as soon as possible and returned to the specified 50/50 mix of Dexcool and water.<P>Side issue -- by that time, all GM radiators and heater cores had no solder in them, using gaskets to seal the tanks to the cores.<P>I found a Saab brochure on antifreeze back in the 1980s. BASF was the manufacturer of their coolant and the publication mentioned that ethylene glycol and lead solder were natural enemies. When the additive package that kept the coolant from eating the solder went away, problems were not far behind. Hence, the necessary drain interval in systems with lead solder and the use of corrosion inhibitor additives back then. Therefore, with lead solder not in the modern cooling systems, that problem went away. Dexcool is an ethylene glycol coolant just the previous green coolant is.<P>With Dexcool having such a long service life, the amount of hazardous materials that would enter the enviroment from coolant changes would be lessened greatly. Plus, it went along with the GM initiative for basically no maintenance for 100,000 miles (other than oil and filter changes).<P>All of these things were begun back when Texaco was 100% Texaco and not a part of big oil that got bigger in recent years. At that time, their website addressed the retrofit issue. It stated that "green antifreeze" systems should be flushed twice to get all of the existing coolant out of the system, then the 50/50 mix of Dexcool/water could be added--but that the coolant would not have a service life of more than 50,000 miles. Why? because there would be enough residual "green" stuff in the system (that had soaked into the metals and such plus the previous additives in there too) to make it a contaminated system. I did find tonight, after I finally found the updated Texaco site on Dexcool, that up to 10% contamination of the Dexcool mixture with green coolant would be acceptable, but would nullify the long term (100,000 or 150,000 miles) protection of the system.<P>Now, in the first few years, some service issues with Dexcool generated some GM service bulletins, plus a few during the past few years too. These bulletins were concerned with specific vehicles too.<P>The worst one was with the 4.3L Chevy V-6 in S-10 vehicles. The bulletin specified that if an accumulation was found on the filler neck of the radiator, to clean it, inspect the radiator neck, and replace the cap with a newer cap. Now, this is where it might be of concern to older vehicles . . . Dexcool reacts with air to form a grainy textured accumulation. What was happening in the S-10s, the cap allowed the coolant level to drop resulting with the radiator not being completely full all of the time. It eventually resulted in the system not pressurizing and more coolant boiling out with more accumulation in the process--as the unpressurized coolant would boil at close to 220 degrees F, which is just past the 195 degree thermostat openning temperature. Yet the pressurized system would be fine to just past 260 degrees. The additional recommendation I came across was to maintain the coolant recovery jug to the "Full Hot" level with a cold engine, with the added coolant ensuring there would be no air in the system.<P>Key thing here, older systems with no coolant recovery jug mechanism would basically be operating as the "low coolant" systems in the S-10, even with a good radiator cap. Therefore, the grainy accumulation could very well form and proliferate in the earlier radiators. Therefore, the implied message for older vehicles would be to install a large capacity coolant recovery system and keep it full.<P>As for the much ballyhooed water pump life issue? Even in the old days of high silicate coolants, water pumps usually lasted about 50,000+ miles anyway. I somewhat doubt that even the most die hard BDE member would drive their vintage cars that far over a 3 year time frame, but I could be wrong. Since the retrofitted Dexcool coolant is only rated for 50,000 miles anyway, it sounds like more expense to use Dexcool and not get any better performance/durability of the coolant and other components.<P>Also, you'd think that water pump sales would have gone away, but we still put them on light trucks under factory warranty even now, but on vehicles where obviously there is some lack of maintenance. With other vehicles, they did basically "dry up". No doubt, Texaco and GM did document added life from Dexcool in that respect--and it makes sense too--but I just don't see that that would be an issue with an older, retrofitted system. Others might differ on that and I respect that.<P>Other than the "Car and Driver" commentary I mentioned earlier, I found a website with a good commentary by John Bruner, a retired GM engineer, on some of the problems with Dexcool systems on new vehicles and what was determined to be the cause. The address for that page is: <A HREF="http://www.imcool.com/articles/antifreeze-coolant/dexcool-johnbruner.htm" TARGET=_blank>www.imcool.com/articles/antifreeze-coolant/dexcool-johnbruner.htm</A> <P>Another revelation from Mr. Bruner's article, the coolant seal tabs that used to be put in all GM cooling systems at the factory are not used with Dexcool. <P>I recommend that Mr. Bruner's article be read and understand how it would relate to a system that does not have, was not designed for, or has a poorly maintained factory coolant recovery system.<P>I found another website that discusses conversion from green coolant to Dexcool. That page is: //autorepair.about.com/library/weekly/aa052601a.htm<P><BR>Finally, the Texaco Dexcool information bulletin is at: //thegenesisnetwork.equilon.com/genesis/prodinfopdf/HAVOLINE . . <BR>That's one long address and you can find it at the #19 search result when you go into Yahoo and put "dexcool" in the search window. Anyway, it's the current information sheet.<P>I also went into the Zerez antifreeze site and looked at the things mentioned by Mr. Bedard. The items he mentioned are there plus some other product information and factory service spec numbers.<P>In the course of these things, I also ended up in the <A HREF="http://www.imcool.com" TARGET=_blank>www.imcool.com</A> site. One of the many cooling system items from their BBS mentioned voltage "in the coolant". Using a digital VOM, place one probe in the liquid coolant and the other on a good ground or negative batter cable. If the value is .2V-.5V, the coolant is still good; .5V-.7V, borderline; greater than .7V is bad. I knew that modern computerized sensor motors had to have good coolant in them for the sensors to function correctly, and this pretty much defines the ranges. The voltages are also related to alkalinity and related things. With the sensors working on small voltage ranges and the coolant being an electrical ground condutor too, it's all related to a certain extent.<P>I recommend that everyone check out these websites and magazine articles and make your own decisions.<P>Thanks for reading through this, I know it's a little long but there is a lot of information to consider and cover. If, by chance the webpage addreses didn't "make the trip" here, email me direct and I'll send them to you.<P>Thanks!<BR>NTX5467