For 1990-2009 cars

# INFORMATION ON SIERRA-BRAND ENGINE COOLANT

REVISION: 08/08/94

THIS BULLETIN IS BEING REVISED TO REFLECT MOST CURRENT INFORMATION ON PROPYLENE GLYCOL ENGINE COOLANT. PLEASE DISCARD BULLETIN 436201 (GROUP REFERENCE 6 - ENGINE). ---------------------------------------------------------------------- REVISION: 04/04/95

THIS BULLETIN IS BEING REVISED TO REFLECT MOST CURRENT INFORMATION ON PROPYLENE GLYCOL ENGINE COOLANT. PLEASE DISCARD BULLETIN 436201A (GROUP REFERENCE 6 - ENGINE). **********************************************************************

#### SUBJECT: INFORMATION ON PROPYLENE GLYCOL ENGINE COOLANT

#### MODELS: 1994 AND PRIOR PASSENGER CARS AND TRUCKS

GENERAL MOTORS HAS BEEN REVIEWING DATA SUPPLIED ON THE PERFORMANCE OF PROPYLENE GLYCOL ENGINE COOLANT IN GM VEHICLES. IT IS OUR CONCLUSION THAT PROPYLENE GLYCOL ENGINE COOLANT WILL PERFORM ADEQUATELY UNDER MOST VEHICLE OPERATING CONDITIONS. AS A RESULT, PROPYLENE GLYCOL ENGINE COOLANT (MEETING PERFORMANCE SPECIFICATION GM 1825M) MAY BE USED IN GM VEHICLES AND WILL NOT AFFECT THE WARRANTY COVERAGE.

PRIOR TO ADDING PROPYLENE GLYCOL ENGINE COOLANT TO THE COOLING SYSTEM, ALL THE EXISTING (ETHYLENE GLYCOL) COOLANT MUST BE REMOVED. THIS CAN BE ACCOMPLISHED EITHER BY UTILIZING WATER-BASED COOLANT FLUSHING EQUIPMENT OR "WATERLESS QUICK CHANGE" EQUIPMENT AVAILABLE IN THE GMDE PROGRAM. AS WITH ANY COOLANT CHANGE PROCEDURE, BE SURE TO THOROUGHLY PURGE THE HEATER CORE AND BLOCK AS WELL AS THE RADIATOR BEFORE ATTEMPTING TO CONVERT THE SYSTEM TO PROPYLENE GLYCOL COOLANT.

FREEZE/BOIL POINT LEVELS ARE DIFFERENT FOR PROPYLENE GLYCOL THAN FOR ETHYLENE GLYCOL ENGINE COOLANT. TO ACCURATELY DETERMINE FREEZE/BOIL PROTECTION LEVEL, IT IS IMPERATIVE THAT COOLANTS NOT BE MIXED. REMOVING ALL THE USED COOLANT AS PREVIOUSLY DISCUSSED RESOLVES THIS CONCERN. FREEZE PROTECTION OF PROPYLENE GLYCOL CANNOT BE DETERMINED USING A STANDARD HYDROMETER. RATHER, A REFRACTOMETER OR TEST STRIP MUST BE USED.

PROPYLENE GLYCOL ENGINE COOLANTS MAY BE RECYCLED IN THE SAME MANNER AS CONVENTIONAL ETHYLENE GLYCOL COOLANT. NO ADVERSE EFFECTS WILL BE ENCOUNTERED IF THESE COOLANTS ARE MIXED PRIOR TO RECYCLING, HOWEVER, THE RATIO OF PROPYLENE GLYCOL COOLANT TO ETHYLENE GLYCOL COOLANT SHOULD BE KEPT LOW TO MINIMIZE THE EFFECTS ON FREEZE POINT MEASUREMENTS.

FIGURES: 0

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.

COPYRIGHT 1995 GENERAL MOTORS CORPORATION. ALL RIGHTS RESERVED.