Possible Clues:

• Oil, informally
• Black gold
• ''Black gold''
• Oil, slangily
• Petroleum nickname
• Drink made with tequila, rum, vodka, gin, bourbon, triple sec, sweet-and-sour mix and Coke
• Oil, to Jed Clampett
• Crude, à la 'The Beverly Hillbillies'
• Crude
• Crude, slangily