INFORMATION ON PROPYLENE GLYCOL ENGINE COOLANT. Saturn Saturn 1991

For 1990-2009 cars

# INFORMATION ON PROPYLENE GLYCOL ENGINE COOLANT

#### SUBJECT: Information on Saturn Engine Coolant

#### TO: Fixed Operation Managers

The following paragraphs describe Saturn Corporation's service position on the use of engine coolants in Saturn vehicles.

Saturn engine coolant P/N 21030365 (one gallon container) and P/N 21030856 (55 gallon drum) have been thoroughly test in Saturn vehicles and meet all requirements of the vehicle's cooling system. Saturn does not test all of the engine coolants available in the market. Therefore, Saturn recommends that when service is required on the engine cooling system of a Saturn vehicle, that it be serviced with the Saturn released engine coolant.

However, traveling circumstances may arise that require the Saturn vehicle cooling system to be serviced/repaired at a non-Saturn facility, which may not have Saturn engine coolant. If this circumstance occurs, the use of engine coolant that is non-phosphate, ethylene glycol based may be used in a Saturn vehicle.

No current engine coolant formulations composed of propylene glycol are approved for use in Saturn vehicles.

#### CAUTION:

BOTH ETHYLENE GLYCOL AND PROPYLENE GLYCOL ARE TOXIC. WHILE PROPYLENE GLYCOL HAS A HIGHER LETHAL DOSE LEVEL THAN ETHYLENE GLYCOL, PARTICULARLY IN ANIMALS, IT SHOULD NOT BE CONSIDERED NON-TOXIC. PROPYLENE GLYCOL COOLANT, LIKE ETHYLENE GLYCOL COOLANT, MUST BE STORED IN A SAFE PLACE WITH NO ACCESS TO CHILDREN OR PETS.

Both ethylene glycol and propylene glycol are completely biodegradable. Actually, ethylene glycol consumes slightly less oxygen than propylene glycol during the degrading process, favoring ethylene glycol. However, used coolant may contain heavy metals which have originated from the vehicle's cooling system. It is for this reason that the EPA regulates used coolant as a hazardous waste if it contains greater than 5 ppm of lead. Used coolant, whether ethylene glycol or propylene glycol based, must be recycled and reused or handled in an environmentally safe manner.

#### NOTICE: The addition of a fully formulated propylene glycol coolant to a vehicle cooling system which contains ethylene glycol coolant could cause the destabilization of various corrosion inhibitors. If destabilization is achieved, the subsequent loss of corrosion protection could occur, causing damage to various cooling system metals.

If ethylene glycol and propylene glycol based coolants are mixed in the vehicle, it will be impossible for the auto-technician to determine the actual ethylene/propylene glycol ratio. Once mixed, conventional methods of determining freeze point (i.e. refractometer, hydrometer) will not be accurate. Both the refractive index and the specific gravity differs between ethylene glycol and propylene glycol.

Because the physical properties of propylene glycol based coolants present possible problems in vehicles designed for use of ethylene glycol coolant, current Saturn coolant specifications must be adhered to. Propylene glycol coolants should not be used in Saturn Vehicles.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.