Review for LEGO set 554 Exxon Fuel Tanker from Brickipedia
“This set was only available in the US, since Exxon-labeled sets were not released in Continental Europe, UK, Australia and Canada, just as Shell sets were not released in the US until 1986. It was a variant of 671 Shell Tanker from 1978, which was the same truck in Shell... More livery. On the right side of the vehicle is a decal saying "Happy motoring".”
Full review at brickipedia.fandom.com