Lesley, you and I are in the same situation. I've got 2 empty propane tanks and two almost full. I had hoped to fill up the four at Costco tomorrow, but don't have enough sap today to empty the two fullish tanks. That means when we get sap tomorrow I'll be running out on Easter Sunday. A gas station fill up will KILL me. I just can't do it! Perhaps I need to suck it up and only fill two tomorrow at Costco. It's still worth the drive to save the $16 for two compared to filling at the local Home Hardware. Dropping $27 or so per tank at the local gas station on Sunday is just so wrong.