In Canada, propane recertification required at 10 years
We have a propane tank with built in gauge from Sam's club. We now know from experience that when the gauge is deep in the red "empty" area, we still have about a gallon of propane left.
While on the subject of propane, we got an unwelcome surprise in Canada when we tried to refill our empty 2nd propane tank. It seems Canada requires recertification every 10 years (12 years in USA), and they seem to actually check the date! They refused to refill the older tank. Fortunately we had enough propane to get us to Alaska in our newer tank, where it seems the USA propane distributors don't seem to bother checking the date.
We have since purchased another new tank.
Dave (AKA John) and Marilyn
04 Dodge Dakota Quad cab 4.7 (primary TV)
08 Subaru Outback 2.5 (alternate TV)