Related Clues:

• It should be changed regularly
• Painter's option
• Squeak remedy
• It's well-supplied
• Standard ___
• Book on which 'There Will Be Blood' was based
• Nigerian export
• It can be crude or refined
• Little squirt, maybe
• Recent commodity index booster
• Atar, for one
• Crude cargo
• Cartel commodity
• Alaska resource
• A splash in the pan