An octogenarian friend of mine, in another state, has an above ground 350
gallon tank of home heating oil that is filled about once a month in the
winter.

The widow lives alone and simply asked me about how to read the tank from
inside the house. I have propane, so my RD3 tools don't seem to work on
kerosene tanks.

Do you have any suggestions for me to research that you have found work
well?