ENGINE OIL REQUIREMENTS/INFO (ALL MD WITH TURBO)

SUBJECT: ENGINE OIL SELECTION REQUIREMENTS

MODELS: ALL 1985-88 W/4-W/7HV FORWARD/TILTMASTER WITH TURBOCHARGED ENGINES (VIN CODES N, H and S)

This bulletin provides background information on selecting the proper A.P.I. (American Petroleum Institute) rated oil which is to be used in W-Series trucks. Technicians must be aware that all oils used in Forward/Tiltmaster turbocharged engines must have a "CD" API rating. The Forward/Tiltmaster Owners Manual states:

"Oils which are not labeled "CD" should not be used. Do not use synthetic oils."

NOTICE: GM Goodwrench 10-30W oil has an API rating of "CC" and must NOT be used in Forward/Tiltmaster turbocharged engines or engine damage may occur.

SELECTING PROPER OIL QUANTITY

Engine oils are labeled on the containers with various API designations of quality. Only oils labeled with the designations CD, or with both designations SF and CD (SF/CD) must be used in Forward/Tiltmaster turbocharged engines.

SELECTING PROPER OIL VISCOSITY

Engine oil viscosity (thickness) has an effect on fuel economy, cold weather starting, and engine durability. Lower viscosity engine oils can provide better fuel economy, however, higher temperature weather conditions require higher viscosity engine oils for satisfactory lubrication.

When choosing an oil, consider the range of temperature the vehicle will be operated in before the next oil change. Then select the recommended viscosity oil from the attached chart. (Figure No. 1)

OIL IDENTIFICATION LOGO

Starting in 1983, a logo (symbol) was added to some oil containers to make proper oil selection easier. The top portion of the logo lists the oil quality by API designation, while the center portion of the logo shows the SAE viscosity grade. (Figure No. 2).

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.