How many letters does the top answer for “smeared or soiled with grease or oil” have?

The most common answer is greasy (6 letters).

Crossword clue: smeared or soiled with grease or oil

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

greasy 6 letters wn-def

smeared or soiled with grease or oil

oily 4 letters wn-def

smeared or soiled with grease or oil

smeared with oil or grease to reduce friction 50% similar → greased, lubricated