INFORMATION ON AUTO TRANS EXTERNAL OIL COOLERS. GMC Truck GMC C Pickup

REVISION: 06/04/98 DIVS INVL 1 5 7

THIS BULLETIN IS BEING REVISED TO ADD THE 1994-1998 MODEL YEARS AND ADD TWO NEW COOLER PART NUMBERS FOR 1996-1998 4L60-E EQUIPPED MODELS. PLEASE DISCARD CORPORATE BULLETIN NUMBER 367103 (SECTION 7 - TRANSMISSION). ______________________________________________________________________

SUBJECT: INFORMATION ON AUTOMATIC TRANSMISSION (AT) EXTERNAL OIL COOLERS

MODELS: 1988-98 CHEVROLET AND GMC C/K MODELS

GMC/CHEVROLET TRUCK HAS AVAILABLE TO OWNERS A HIGH EFFICIENCY AUTOMATIC TRANSMISSION OIL COOLER. THIS COOLER IS ALSO AVAILABLE AS RPO KNP FOR MANY MODELS IN THE C/K LINE. THIS NEW AIR TO OIL COOLER OFFERS EXCELLENT COOLING ABILITY.

BECAUSE THE HIGH EFFICIENCY OFFERED BY THIS COOLER EXCEEDS MANY AFTERMARKET COOLERS, WE ARE OFFERING THIS COOLER IN KIT FORM FOR DEALER INSTALLATION. THIS COOLER MAY BE INSTALLED ON BOTH NEW AND USED VEHICLES THAT ARE IN APPLICATIONS WHICH CREATE HIGHER TRANSMISSION OPERATING TEMPERATURES. THESE APPLICATIONS TYPICALLY INCLUDE HIGH FRONTAL AREAS (EITHER ON THE TRUCK OR TRAILER), OR HEAVY LOADS WHERE VEHICLES ARE OPERATED AT HIGHER ROAD SPEEDS.

THE TRANSMISSION OIL COOLERS LISTED BELOW HAVE BEEN THOROUGHLY TESTED AND WILL PROVIDE THE EXTRA TRANSMISSION OIL COOLING THAT TRUCKS USED IN THESE APPLICATIONS MAY NEED. THESE KITS CAN BE INSTALLED IN APPROXIMATELY 1.2 HOURS AND INCLUDE THE FOLLOWING COMPONENTS:

-COOLER -MOUNTING BRACKETS -CLAMPS -FLEXIBLE LINES -FASTENERS -INSTALLATION INSTRUCTIONS

IMPORTANT: THE INSTALLATION OF ANY AUXILIARY TRANSMISSION OIL COOLER WHICH IS LOCATED AHEAD OF THE A/C CONDENSER AND RADIATOR WILL REDUCE AIR FLOW THROUGH THESE COMPONENTS. A SLIGHT INCREASE IN ENGINE OPERATING TEMPERATURES, MORE FREQUENT FAN CLUTCH ENGAGEMENT AND A SMALL DECREASE IN A/C PERFORMANCE SHOULD BE CONSIDERED NORMAL. VEHICLES EQUIPPED WITH AN EXTERNAL COOLER AND OPERATED IN COLD CLIMATES SHOULD USE DEXRON(R) III IN THEIR TRANSMISSION. THIS FLUID OFFERS IMPROVED LOW TEMPERATURE VISCOSITY AND HIGH TEMPERATURE OXIDATION STABILITY.

PARTS INFORMATION

PART NUMBER DESCRIPTION APPLICATION 12546251 COOLER KIT 1988-95 C/K 1,2,309,310,314 W/4.3L,5/0L,5/7L,6.2L,6.5L AND 4L60,4L60-E,3L80,4L80-E EXCEPT 5D5, C5B 12546252 COOLER KIT 1988-95 C/K 1,2,309,310,314 W/7.4L AND 3L80,4L80-E EXCEPT EXPORT 12546253 COOLER KIT 1988-95 C/K 310,314,318 W/4L80-E AND C5B 15161200 COOLER KIT 1996-98 C/K 1,2 W 4.3L, 5.0L AND 4L60-E 15151337 COOLER KIT 1996-98 C/K 1,2 W 5.7L AND 4L60-E

RPO DEFINITIONS C5B - 15,000 LBS. GVWR 5D5 - RADIATOR BOOSTER FAN

PARTS ARE EXPECTED TO BE AVAILABLE ON 6/15/98 FROM GMSPO.

FIGURES: 00 ATTACHMENTS: 00

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.