filling (n.)youdaoicibaDictYouDict
c. 1400, "that which fills or fills up," verbal noun from fill (v.). Dentistry sense is from 1848. Filling station attested by 1915.
gasoline (n.)youdaoicibaDictYouDict
"lightest volatile liquid obtained from distillation of petroleum," 1864 (alternative spelling gasolene is from 1865), from gas (n.) + -ol (probably here representing Latin oleum "oil") + chemical suffix -ine (2). Shortened form gas was in common use in U.S. by 1897. Gas station as a fuel filling station for automobiles recorded by 1924.