Historical clue formulations

• Oil, they say — 2026-05-28
• Oil, slangily — 2025-02-07
• Oil, informally — 2021-08-07
• *Oil, jocularly — 2017-12-07
• Crude, in slang — 2015-08-15
• Drink made with tequila, rum, vodka, gin, bourbon, triple sec, sweet-and-sour mix and Coke — 2014-03-21
• Crude, slangily — 2010-03-06
• Black gold — 2010-01-14
• Oil, slangily — 2005-05-18
• Slang for 55-Across — 2003-02-23
• Oil — 1995-12-23