* 3.1L V6: This engine typically holds around 4.5 quarts of oil.
* 3.8L V6: This engine typically holds around 5 quarts of oil.
Check your owner's manual: The most accurate information will be in your vehicle's owner's manual. It will list the exact oil capacity for your specific engine. If you don't have the manual, you can often find a downloadable version online through the Buick website or a third-party site selling repair manuals.
Failing that, look for a sticker under the hood; sometimes the oil capacity is listed there.