What motor oil should I use for my 2003 buick regal ?

It is likely 5W-30. Often times, it's written on the oil filler cap. My advice is to use a full-synthetic engine oil (e.g. Mobil 1) and change the oil and filter every 6,000 miles or 6 months, whichever comes first. When you have 25,000 miles on the car, I recommend that you use Mobil 1 Synthetic Multi-Vehicle ATF, when you change the transmission fluid and filter. If you do this, you will be far ahead of the game.

It is likely 5W-30. Often times, it's written on the oil filler cap. My advice is to use a full-synthetic engine oil (e.g., Mobil 1) and change the oil and filter every 6,000 miles or 6 months, whichever comes first. When you have 25,000 miles on the car, I recommend that you use Mobil 1 Synthetic Multi-Vehicle ATF, when you change the transmission fluid and filter. If you do this, you will be far ahead of the game.
Thanks for the info bro. with all my love the dummie

SAE 10W-30 (for temperature ranges above 0°F) 5W-30 for colder climates (40°F on down to below 0).

The 6K change interval txgreasemonkey gave is a good number unless you drive it hard all the time or if it runs hot.

This should all be in your owners manual. If you don't have one, here's a link to one: http://www.analogstereo.com/pdf/om/2003regal.pdf

SAE 10W-30 (for temperature ranges above 0°F) 5W-30 for colder climates (40°F on down to below 0).

The 6K change interval txgreasemonkey gave is a good number unless you drive it hard all the time or if it runs hot.

This should all be in your owners manual. If you don't have one, here's a link to one: http://www.analogstereo.com/pdf/om/2003regal.pdf
Thanks for the info