The manual will specify the type (conventional, synthetic blend, or full synthetic) and the viscosity grade (e.g., 5W-30, 10W-40). Failing to use the correct oil can damage your engine.
If you don't have the owner's manual, you can try:
* Buick's website: Their website might have resources for older models.
* Online parts stores: Websites like AutoZone, Advance Auto Parts, or Napa Auto Parts allow you to search by year, make, and model to find the recommended oil. Be sure to check multiple sources to verify.
* A local mechanic: A qualified mechanic can tell you what type of oil your Buick needs based on the engine.
Don't rely solely on general information; always consult your owner's manual or a reliable source for the specific oil requirements of your 1996 Buick.