Possible Clues:

• What a topping thing to do
• Costly gas purchase
• Standard 28-Down purchase
• Fifty-fifty if you bring it to the top
• Perhaps double L, if you want to put in all that will fit
• Double L, if one is to replenish this (4, 2)
• Put petrol in car
• Double L, if it's great gas you want
• Top off
• Come close to tears