Oldsmobile Silhouette high beam headlight bulbs use 9004 or 9005 size, while low beam headlight bulbs use 9004 or 9006 size. The replacement chart covers 1990 to 2004 model years with corresponding bulb size specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The 9004 bulb is a dual-filament halogen type operating at 12V with a P29t base and a 65W/45W wattage rating, where the higher wattage serves the high beam filament and the lower wattage serves the low beam filament. This single bulb handles both functions within one housing.
Because the 9004 carries dual filaments, the Oldsmobile Silhouette from 1997-2004 uses the same bulb for both the high beam and low beam headlight positions, meaning one part number covers both functions for those model years.
The 9005 and 9006 bulbs are each single-filament halogen types, which means each bulb serves only one lighting function. On the Silhouette from 1990-1996, the high beam and low beam positions therefore require two separate and distinct bulb types.
The 9005 operates at 65W with a P20d base, while the 9006 operates at 55W with a P22d base. The differing wattage and base types make these two bulbs physically and electrically incompatible with each other, and neither is interchangeable with the 9004.
All three bulb types conform to ANSI standards applicable in the United States and Canada, placing them within a standardized specification framework for halogen headlight bulbs in those markets.
The P29t, P20d, and P22d base designations each represent a distinct physical connector configuration. Substituting one base type for another is not supported by the specifications, as the socket designs do not correspond across these three bulb families.
The transition from the 9005/9006 pairing to the 9004 occurred between the 1996 and 1997 model years of the Silhouette, reflecting a shift from a two-bulb headlight system to a single dual-filament bulb per headlight assembly.