Someone took a oven that is kosher for Pesach from a gemach to use on Pesach. They cooked in it a kugel and by mistake they put in it oil made from kitniyos (had a hechsher on it that it’s good for sephardim). They didn’t eat the kugel, however what’s the din on the oven?
The oven is fine.
Many are lenient for belios of kitniyot, certainly after twenty four hours have passed (Maharalnach 121; Peri Chadash 496:24), and the more so for the next year, for which it is simple that there is no reason for stringency.
This is all the more true for oil, for which the question of kitniyot is not clear cut.