This bulletin cancels and replaces PSB 90-641-102 and PSB 90-645-113 which should be discarded.
A revised oil pan gasket has been released to improve oil pan sealability. This new gasket contains circular spacers on each side of the oil pan bolt holes which limit the compressibility of the gasket to maintain gasket integrity, even if the bolts are over-tightened. The revised gasket is available from CANSPO by ordering P/N 3522550. The previously-released oil pan gasket has been cancelled.
To allow this improved gasket to be used on 1982-1985 Brougham, 1987-1989 Allante, and 1982-1990 DeVille, Fleetwood, Eldorado, and Seville engines (before 1990 VIN breakpoint C-354000, E-619000, K-826000) the oil pan attaching bolts must also be updated. The revised bolts have a wide washer head to allow bolt torque to press directly upon the gasket's circular spacers and also incorporate a locking system to maintain proper bolt torque.
Revised bolts are available from CANSPO by ordering P/N 3525195 (20 required) for all cars except 1987-1991 Allantes which require P/N 3525196 (20 required) due to the increased flange thickness of the cast aluminum oil pan. Once updated with these revised bolts, future service can be accomplished with only the revised gasket.
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.