Oldsmobile Alero front and rear turn signal bulbs utilize 3157NA and 3057 sizes respectively. The replacement chart covers 1999 through 2004 model years with corresponding bulb specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Oldsmobile Alero uses two distinct bulb types across its front and rear turn signal positions for the 1999-2004 model years.
The 3157NA is the specified front turn signal bulb for the Alero across all six model years in the dataset.
Both the 3157NA and 3057 are ANSI-standardized dual-filament wedge bulbs of the T25 type, rated at 12V with a 27W high-filament and 7W low-filament output.
The dual-filament design allows a single bulb to serve two lighting functions, typically combining the turn signal with a running or parking light in the same housing.
The 3157NA designation indicates a natural amber glass envelope, which produces an amber-colored output without relying on a colored lens or housing to filter white light.
The 3057 is the specified rear turn signal bulb for the Alero across all six model years in the dataset, and it shares the same T25 form factor and 12V/27W/7W electrical ratings as the 3157NA.
Despite their identical physical form factor and electrical ratings, the 3157NA and 3057 are not interchangeable in all applications, as the natural amber glass coating on the 3157NA affects light output color in ways that may not meet requirements where a clear bulb behind an amber lens is specified.
The T25 wedge base is a press-fit type with no separate metal base pins, relying on the glass envelope itself to make contact within the socket.