ENGINE OIL LEVELS RE-CALIBRATED DIPSTICK

VEHICLES AFFECTED: 1982-1985 Rear Wheel Drive Deville and Broughams 1982-1985 Eldorados And Sevilles

Owners of HT4100 equipped Devilles, Fleetwoods, Eldorados and Sevilles built between 1982 and 1985 may experience some confusion regarding proper engine oil level shown on the dipstick. Product Service Bulletin 85-6-226 discusses this same situation for Front Wheel Drive 1985 Devilles and Fleetwoods.

Confusion results from oil levels not reading within the full range when the oil level is checked even with a known quantity of oil in the crankcase. Cadillac research indicates that the following factors contribute to this situation:

- Dipstick Graphics - Calibration Revisions - Measurement Techniques

Dipstick Graphics

In an effort to compensate for different oil fill levels depending upon whether or not the oil filter is changed, HT4100 engine dipsticks have, in the past, included a crosshatched area indicating the 'full range', Figure 1. This may cause some owners to believe that the crankcase is not adequately filled if the oil level is between the crosshatched area and the add mark. While this is an incorrect belief, new dipsticks have been released with the crosshatched section extending from the full mark to the add mark, Figure 1. These dipsticks carry P/N 1640021 for 1982-1985 Rear Wheel Drive Deville and Brougham, and P/N 1640022 for 1982-1985 Seville and Eldorado.

Calibration Revisions

Recent research indicates that the 1982-1985 rear-wheel-drive Deville, Brougham dipstick (P/N 1626573) is calibrated improperly. The newly released part (P/N 1640021) with revised crosshatched markings has also been recalibrated to correct this condition. The 1982-1985 Eldorado, Seville dipstick is already calibrated correctly and is revised to include the extended crosshatch area only.

Measurement Techniques

Obtaining an accurate dipstick measurement depends upon many factors. The two most important factors are: 1) temperature of the oil; and 2) length of time since the engine was shut off. In order to obtain an accurate dipstick measurement of the amount of oil actually in the crankshaft, the engine must be run until is it at normal operating temperature and oil temperature has stabilized. This can be as little as 5 minutes following an oil change on a hot engine to as much as 30 minutes operation in cold climates. After the engine is shut down, adequate time must be allowed for the oil to drain back into the oil pan. This takes 10-20 minutes on a new engine. The condition of cylinder head drain back passages affects drain back time.

Measurements made under other conditions will not indicate accurately on the dipstick. The dipstick can indicate a maximum of 1/2 quart low if the oil is checked within a couple of minutes following a brief leak check after an oil change. This condition is normal and should be taken into consideration if oil level is measured under other circumstances.

Dipstick Installation

Before installing a new dipstick, the dipstick tube length should be measured as indicated in Figure 2. If this dimension is between 11.11cm to 11.27cm (4 3/8 in. and 4 7/16 in) the tube is correct and the dipstick should be replaced. If the tube dimension is not between these dimensions, replace both the tube and the dipstick according to the procedure in the Service Information Manual.

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.