Related Clues:

• Shell game?
• Valdez cargo
• It gets checked with a stick
• See 123-Across
• Well-gotten gain?
• Slippery substance
• Prudhoe Bay find
• Contents of some barrels
• Change it regularly
• Slick stuff
• With 'of' and 51-Across, a facial moisturizer
• Natural resource
• Drilling goal
• It can be hydrogenated
• Iraqi resource