1. Find your car's year and engine type: This information is usually found on your vehicle's registration, the sticker on the driver's side doorjamb, or in your owner's manual.
2. Consult a repair manual specific to your year and engine: A Haynes or Chilton manual (available online or at auto parts stores) will have diagrams showing the exact location of the oil filter. You can also often find this information online through forums dedicated to Buick Regals or general car repair websites.
3. Search online for "[Your Year] Buick Regal [Your Engine] oil filter location": A specific search like this will often yield images and videos showing the filter's location.
Without knowing the specific year and engine, I can't give you a precise answer. The filter is usually somewhere near the engine, but it can be in different positions depending on the model.