Oleo is a term for oils. It is commonly used to refer to a variety of things:
Colloquial term for margarine, a.k.a. oleomargarine
Oleic acid
Oleo strut, a type of shock absorbers on aircraft landing gear
"Oleo" (composition), a composition by Sonny Rollins
Oleo (Grant Green album), a 1962 album by Grant Green featuring the above composition
Oleo (Lee Konitz album), a 1975 album by Lee Konitz featuring the above composition
Oleo (Joe McPhee album), a 1983 album by Joe McPhee featuring the above composition
Óleo, a city in the São Paulo state in Brazil
GNU Oleo, a (defunct) spreadsheet program
Oleo drop, a kind of theater curtain