overhaul has 8 distinct synonyms spread across 4 of its 4 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. WordNet records no antonym for it — antonymy is a relation between word forms rather than concepts, so it is deliberately sparse.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
periodic maintenance on a car or machine
“it was time for an overhaul on the tractor”
the act of improving by renewing and restoring
“they are pursuing a general program of renovation to the entire property”
make repairs, renovations, revisions or adjustments to
“You should overhaul your car engine”
Synonyms, antonyms and the broader and narrower relations for overhaul come from Princeton University’s WordNet. Full sources and licences.