GM Service Manual Online
For 1990-2009 cars only

GRADUAL LOSS OF POWER CRANKCASE CLEANER ADDITIVE

VEHICLES AFFECTED: 1976-84 'T' Series

Some high mileage 'T' Series may experience a gradual loss of power. This condition may be the result of deposit accumulation on internal engine components which results in a loss of engine compression. This condition usually results from improper oil maintenance.

On vehicles equipped with the Computer Command Control system, a Code 44 may be stored.

The condition can generally be corrected by adding a can of Crankcase Cleaner, P/N 993288 (not Top Engine Cleaner or EOS), to the engine oil.

NOTICE: Follow the instructions on the can.

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.