In 3-quart saucepan, place potatoes; add just enough water to cover. Heat to boiling; reduce heat. Cover and simmer 15 to 20 minutes or until potatoes are tender; drain.
In same saucepan, mash potatoes, oil and salt with potato masher just until lumpy. Gradually add buttermilk, mashing until blended but still lumpy. (Amount of buttermilk needed to make potatoes creamy depends on variety of potatoes used.) Season to taste with pepper. Stir in chives.