Oldsmobile Cutlass Supreme Back Up Light Bulb Size

The Oldsmobile Cutlass Supreme back up light utilizes 3057, P21W, and 1156 bulb sizes depending on the specific version of the vehicle. Available data for the bulb sizes covers the range from 1967 through 1997.

The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.

Bulb Size by Year Range

Years	Bulb Size
1989-1997	3057
1967-1987	1156

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Dual-filament wedge bulb (T25). 12V, 27W/7W.	3057
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. 12V, 21W.	1156

Other Locations

Additional Notes

The Oldsmobile Cutlass Supreme uses two distinct back up light bulb types across its model years: the 3057 and the 1156, both of which conform to ANSI standards recognized in the United States and Canada.
The 3057 bulb is a dual-filament wedge type in a T25 form factor, rated at 12 volts with filaments drawing 27 watts and 7 watts respectively.
The 1156 bulb is a single-filament type mounted on a BA15s bayonet base, rated at 12 volts and 21 watts.
Because the 3057 carries two filaments and the 1156 carries only one, the two bulb types are not interchangeable despite both operating on a 12-volt system.
The BA15s bayonet base of the 1156 is a single-contact fitting, which is physically incompatible with the wedge socket used by the 3057, further preventing cross-substitution.
The Oldsmobile Cutlass Supreme (1967-1987) specifies the 1156 bulb for the back up light position across that entire span of model years.
The 3057 bulb is specified for the 1989-1997 model years, representing a change in bulb type relative to the earlier generation of the vehicle.
The higher primary filament wattage of the 3057 (27W) compared to the 1156 (21W) means the later-generation back up lights produce greater luminous output from the primary filament.