How many letters does the top answer for “a flammable hydrocarbon oil used as fuel in lamps and heaters” have?

The most common answer is kerosene (8 letters).

Crossword clue: a flammable hydrocarbon oil used as fuel in lamps and heaters

2 answers found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

kerosene 8 letters wn-def

a flammable hydrocarbon oil used as fuel in lamps and heaters

kerosine 8 letters wn-def

a flammable hydrocarbon oil used as fuel in lamps and heaters