Oldsmobile Delmont 88 front turn signal bulbs use 1157NA size while rear turn signal bulbs use 1157 size. The replacement chart covers 1967 to 1968 production 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 1157NA and 1157 bulbs are the two types specified for the Oldsmobile Delmont 88, covering the 1967-1968 model years across front and rear turn signal positions.
Both the 1157NA and 1157 are dual-filament bulbs, meaning each unit contains two separate filaments operating at different wattages within a single housing.
The higher-wattage filament in both types operates at 21W and serves the turn signal function, while the lower-wattage filament operates at 5W and typically serves a parking or running light function.
Both bulb types share the BAY15d bayonet base, a two-pin offset base design that physically distinguishes it from single-filament bayonet bases and prevents incorrect installation of a single-filament replacement.
Both types are rated at 12V, consistent with the 12-volt electrical systems standard in passenger vehicles of that era.
The 1157NA specified for the front turn signal positions on the Oldsmobile Delmont 88 features natural amber glass, which produces an amber light output directly from the bulb itself.
The 1157 specified for the rear turn signal positions uses clear glass, meaning any amber color in the light output is produced by the lens rather than the bulb.
Because the 1157NA and 1157 share the same BAY15d base and voltage ratings, they are physically interchangeable, though substituting one for the other will affect whether the amber color originates from the bulb or the lens.
Both the 1157NA and 1157 conform to ANSI standards recognized in the United States and Canada.