Historical clue formulations

• Petrol units — 2019-10-16
• Petrol measures — 2013-07-31
• Petrol measures — 2012-12-12
• There are 50 in a keg of Newcastle — 2010-09-17
• Petrol measures — 2006-04-07
• Petrol units — 2002-02-01
• Petrol amounts — 1994-01-09