I'm surprised people are stuck arguing on whether the slang of "pot" would survive to the 24th-25th centuries, but haven't batted an eye at "grease monkey."I'm pretty sure use of the word "pot" in that scene was just a play on words joke that didn't stick the landing for some people. I chuckled but maybe only because I'm from the era when "pot" "weed" and "Mary Jane" were in use. I'm often surprised by the things fans will pick out of an episode to clutch their pearls over.
I would guess that internal combustion engines that use petroleum based fuels wouldn't be a common thing to know (at least that's the feeling you get from what I remember of Tom Paris's love of cars) and that "grease monkey" might have gone through limited usage in 300 years time.