The fuel tank size in a 1989 Oldsmobile Cutlass varies slightly depending on the model (Supreme, Calais, Cruiser, etc.) and whether it had a specific option package. However, the most common fuel tank size for a 1989 Oldsmobile Cutlass is
15 gallons.
To be completely certain, you should check your owner's manual or the sticker located inside the driver's side doorjamb.
