here is the info, I got it
HERE , it's a pdf file only.
--------------------------------------------------------
Cooling System
Conditions on Vehicles Equippedwith DEX-COOL™
General Motors made DEX-COOL™
Extended Life Coolant standard equipmentin all North American-built vehicles(except Saturn) beginning in the 1996model year. Some assembly plants made the conversion over the 1995 Memorial Day shutdown, and all remaining plants were converted for the 1996 model startup.
For the post-Memorial Day built 1995 models filled with DEX-COOL™ and all 1996 models, the coolant maintenance/change interval is 5 years or 100,000 miles, whichever occurs first. In 1997, that interval was increased to 5 years or 150,000 miles, whichever occurs first, which is where it remains today. Several important factors contributed to the decision for GM to be a pioneer in the conversion to extended life coolant. The convenience and financial benefit to the customer of not having to change coolants as often is obvious. Additionally,
the result of having less used coolant to dispose of has the potential to result in significant benefits to the environment. GM also has realized significant increases in water pump durability, and radiator and heater core life. DEX-COOL™ is a non-silicated coolant, while most conventional green coolants contain silicates. One undesirable property of silicates is that they are abrasive and over time can contribute to wear of water pump seals, as well as
other components. Overall, DEX-COOL™ Extended Life Coolant has performed very well in GM vehicles. However, for a combination of reasons, a few models experience varying
degrees of contamination to the radiator cap and/or coolant recovery bottle. In some cases, if the contamination is left unchecked, it can cause problems in other areas of the engine cooling system. We’ll try to assist you in determining the specific type of contamination present, and discuss the most appropriate correction. We’re limiting our discussion to
cooling systems that use a drop-center design radiator cap, and a non-pressurized coolant recovery bottle. The Radiator Cap When a cooling system is not full, the air pocket that is created in the radiator provides a "beachhead" where contaminants can deposit. This occurs much like sand is deposited by waves on the beach. In cooling systems that use a drop-center cap and non-pressurized coolant recovery bottle, these contaminants can deposit in the valve mechanism of the radiator cap. Once the capbecomes contaminated and ceases to
function as designed, chances are that the system will begin to lose additional coolant more rapidly. This is because once the radiator cap fails to hold pressure, a 50/50 mix of coolant and water will boil at 226 degrees Fahrenheit, instead of 265 degrees Fahrenheit, at 15 PSI. By boiling at a lower temperature, it is much easier to exhaust the capacity of the coolant recovery bottle as the coolant expands through the failed cap at the lower temperature. When the system cools off, less coolant will then be available to be drawn back into the radiator. After several cycles under these conditions, the level of coolant in the radiator
can be significantly reduced and the coolant recovery bottle will be empty. It is for this reason that the condition and functional ability of the radiator cap is so important. Always test the functional performance of any radiator cap whenever cooling system performance is in
question, and replace any cap that does not hold the specified pressure. When removing a radiator cap, be sure to wipe off all sealing surfaces prior to replacement, in order to ensure a proper seal. There are only a few models where the system design appears sensitive to
this type of contamination. Although the contaminant may be similar looking, different
models usually have different recommended repairs. That’s because the makeup of the contaminant is often characteristic to a model or engine family. Because of this, each model should be carefully evaluated to assure the appropriate repair is being made. The most effective method of preventing, minimizing or eliminating the affects of contaminants is to always maintain the cooling system (including the recovery bottle) at its recommended full level and ensure the radiator cap is functioning properly. S/T Truck Equipped with 4.3L V6 Bulletin 99-06-02-012B outlines the most effective repair for this model. The contaminant has been identified as iron oxide, and the cleaning material recommended in the bulletin was
selected because it was proven to be the most effective at cleaning this type of contaminant. It is very important to follow the steps outlined in the bulletin p re c i s e l y. Cases where the pro c e d u re was not effective have almost always been traced to substitution of another
cleaning material or the pro c e d u re was not strictly adhered to. The most common mistakes have been:
1. Running the flush while the engine operating temperature is too l o w. Heat acts as a catalyst in this p ro c e d u re, and if the temperature of the system is not maintained according to the bulletin specifications, the cleaning will not be eff e c t i v e .
2. Failing to correctly assess the level of contaminants in the radiator before
beginning. NOTE: As stated in the bulletin, it’s important to determine if coolant is able
to flow through the third row down from the top of the radiator. If not, the radiator
core must be replaced before the flush procedure. This is because the cleaner
must be able to flow past the contamination in order to clean it. In cases where
the system can’t achieve sufficient flow around the contaminants, the cleaner
cannot be effective.
W Car / U Van Equipped with 3.1L or 3.4L V6
Bulletin 00-06-02-004 describes the appropriate repair procedure for the issues most often seen on these models. Although similar in appearance to the S/T issue, the material on the radiator caps of these models contains no iron oxide. It is much more gelatin-like in texture and is usually comprised of sealer pellet residue, hose material and/or other contaminants.
It is very rare to see cases where the contamination evidenced on these radiator caps has spread beyondthe radiator neck. If contamination is suspected beyond the radiator neck, you may choose to remove the radiator end tanks for further inspection. Replacement of the radiator cap, wiping out the radiator neck and topping off the system is all that is normally recommended for these models. Unless other symptoms are present, it is not necessary to flush the cooling system or replace the coolant on these models before their published maintenance/change interval.
2000 LeSabre and Bonneville Equipped with 3.8L V6
Concerns on these models typically center around what is perceived as discolored coolant (usually dark and rust colored in appearance) and a ring of contamination around the inside of the coolant recovery bottle. Analysis has determined that both of these consist of excess sealer pellet material that was inadvertently installed at the assembly plant. Sealer pellet installation has since been discontinued on these models. Cleaning the coolant recovery bottle, topping up the system and checking the cap for proper function is all that is required on these models. Finally, as stated in bulletin 99-06-02-012B, the radiator cap is not a good indicator of the general condition of the cooling system. Typically the underside of the radiator cap will exhibit a greater amount of contamination than the rest of the system, due
to the "beach effect described earlier. Likewise, the color of the coolant is also not a good indicator of its general condition. Due to fading of the dyes used with DEX-COOL™, the
coolant in some vehicles may appear pink after time. The addition of sealer pellet (stop leak) material can turn the coolant color to dark red or maroon. As a rule, color alone is not an
indication of the quality level of the coolant and does not affect its performance. When performing repairs for S/T trucks, U vans and W cars, it may help to replace the standard radiator cap with a Standt model 10230 or 11230 radiator cap. These caps have a spring
center design that may be less sensitive to the effects of low coolant contamination. You should also top off the radiator and fill the coolant recovery bottle to the hot mark when cold.
These measures will combine to guard against the vehicle operating with the cooling system low on coolant. Inform the customer to check the level of the coolant recovery bottle regulary
and to maintain it at the proper level by adding a 50/50 mix of DEX-COOL and water whenever it’s found to be low.
DEX-COOL™ continues to perform extremely well in the majority of GM vehicles, and has provided a competitive performance and environmental advantage. Other manufacturers
are recognizing these benefits. At present, in addition to all North American-built GM vehicles, Texaco extended-life coolant (DEX-COOL™) technology is either in use or approved for use
by several other European and North American manufacturers. For those vehicles that may potentially be affected by contamination, the most effective method of eliminating any risk of the contaminants is to maintain the cooling system (including recovery bottle) at its full-recommended level, and ensure the radiator cap is functioning properly.
