Buick Opel Dome Light Bulb Size

The Buick Opel dome light requires bulb size 67 or 257 depending on the specific application for the interior lighting system. Data for the bulb sizes covers the range from 1976 through 1979.

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
1979	67
1976-1978	257

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. Lower wattage variant of 1156. 12V, 8W.	67
ANSI standard (US & Canada). Festoon or BA9s base instrument bulb. 12V, 2W.	257

Other Locations

Additional Notes

The 1979 Buick Opel dome light uses the 67 bulb, while the 1976-1978 model years use the 257 bulb, making these two groups incompatible with each other despite serving the same function.
The 67 bulb operates at 12V and 8W with a BA15s single-contact bayonet base, classifying it as a single-filament bulb in the same family as the 1156 but at a lower wattage output.
The 257 bulb operates at 12V and 2W, representing a significantly lower power draw than the 67, and is available in either a festoon or BA9s base configuration.
Both the 67 and 257 are ANSI-standardized bulbs rated for use in the US and Canada, meaning they conform to a defined set of electrical and physical parameters within those markets.
The BA15s base of the 67 bulb is a single-contact bayonet fitting, which is not interchangeable with the BA9s base variant of the 257, as the two base types differ in contact design and socket size.
The festoon configuration of the 257 bulb is a cylindrical tube-style lamp held in place by spring clips at each end, which is physically distinct from any bayonet-base format and requires a different socket type.