Oblivious means "unaware," "unmindful," "lacking memory of something." Forgetful implies a faulty memory or a tendency not to remember. Oblivious stresses unawareness, unresponsiveness, and inattentiveness."Jackie was totally oblivious of her surroundings." "Because I was forgetful, I left the percolator plugged in all afternoon." Oblivious has been broadened in meaning to include unconsciousness: "In a deep coma, Betsy was oblivious to the world." (Oblivious may be followed by to or of.) In most instances, forgetful is preferable, because more readily understandable, to oblivious in the senses of "bemused," "abstracted," "unaware," and even "absent-minded."
Dictionary of problem words and expressions. Harry Shaw. 1975.