Buick Skylark Headlight Bulb Size

Additional Notes

• The 9004 bulb is the most widely used type across the Buick Skylark's headlight specifications, covering both high beam and low beam positions for the 1992-1998 model years. It is a dual-filament halogen bulb rated at 12V with a 65W high beam filament and a 45W low beam filament, fitted with a P29t base, which allows a single bulb to serve both beam functions within one housing.
• The 1989-1991 Skylark uses separate single-filament halogen bulbs for each beam position: the 9005 (65W, P20d base) for the high beam and the 9006 (55W, P22d base) for the low beam. Although the 9005 and 9006 share a similar physical profile, they are not interchangeable due to differences in their base configurations and wattage ratings.
• Sealed beam units, which were standard across the earlier Skylark model years, are not bulb-replaceable components. The entire lens, reflector, and filament assembly is replaced as a single unit when the light fails or is damaged.
• The H6054 sealed beam unit, a 5x7-inch rectangular format rated at 12V, was used for both high beam and low beam positions on the 1980-1985 Skylark. Its use in both positions means a single part number covers the full headlight assembly for those years.
• The 1986-1988 Skylark used different sealed beam types for the high and low beam positions. The high beam used the H4651, while the low beam used either the H4656 (1986 and 1988) or the H4652 (1987). All three are 4x6-inch rectangular sealed beam units, but they are distinct part numbers and are not interchangeable across beam positions.
• The H6024, a 7-inch round sealed beam unit, was used on the 1975-1979 Skylark for both beam positions, as well as on the 1954 model year. The H5001 and H5006, both sealed beam units used on the 1961-1972 Skylark, differ in physical format: the H5001 is a 4-inch square unit used for the high beam, while the H5006 is a 5.75-inch round unit used for the low beam.
• All bulb and sealed beam types listed across the Skylark's specifications conform to ANSI standards applicable in both the United States and Canada, indicating regulatory consistency across the full range of covered model years.