Buick Riviera Headlight Bulb Size

Additional Notes

• The Buick Riviera's high beam headlight specification uses three distinct bulb types across its model history: the H5001, H4651, H4701, and 9005, each representing a different headlight technology era and physical format.
• The 9005 and 9006 are single-filament halogen bulbs used in the Buick Riviera from 1988-1999 (excluding 1994). The 9005 operates at 12V and 65W with a P20d base for high beam duty, while the 9006 operates at 12V and 55W with a P22d base for low beam duty. These two base types are not interchangeable despite their physical similarity.
• From 1986-1987, the Riviera used 7-inch round sealed beam units: the H4701 for high beam and the H4703 for low beam. These are complete sealed assemblies rather than replaceable bulbs, meaning the entire headlight unit is replaced when the light fails.
• The H4651, H4652, and H4656 are all 4x6-inch rectangular sealed beam units used across the 1975-1985 model years. The H4652 is noted as a variant of the H4651. All three are sealed assemblies operating at 12V.
• The low beam specification for the Buick Riviera shows variation within the 4x6-inch sealed beam era, with the H4652 fitted in 1975-1978 and 1982-1983, and the H4656 fitted in 1979-1981 and 1984-1985, while the high beam used the H4651 throughout that entire period.
• From 1963-1974, the Riviera used 4-inch square sealed beam units (H5001) for high beam and 5.75-inch round sealed beam units (H5006) for low beam. Both are sealed assemblies operating at 12V and are replaced as complete units.
• All bulb and sealed beam types listed across the full specification range conform to ANSI standards applicable in the United States and Canada.
• The transition from sealed beam headlight units to replaceable halogen bulbs in the Riviera occurred between the 1987 and 1988 model years, at which point the H4701 and H4703 sealed units gave way to the 9005 and 9006 halogen bulbs respectively.