Eastern There are 2 products.

oil gauging paste can be used with oil measuring tape,
oil gauging tape,oil dipping tape, rod or calibrated line
to determine the the product level on light or clear products.
Successfully gauge for gasoline, crude oils,
kerosene, Jet Fuels, Naptha and various other gas oils
and chemicals,
Apply the paste in the area that the level is expected
to appear. When the paste comes in contact with water
it will immediately change from Pink to white, marking
the level,
Water finding paste,Oil measuring tape are needed by most of the
ship/oil tanker,gas station. If you are ship chandler, you can get
some stock of these once your customer(ship-owner) need them,