Situation One gender of food spills in an oven. You later heat utensils and food of the opposite gender in that oven to 120° F (49° C) or more.
Status The utensils and food may become non-kosher, due to the residue's vapor.
What To Do Consult a rabbi.
Note This applies whether the oven is kosher or non-kosher, the residue is dry or liquid, or the utensils or food later placed in the oven are covered or not covered.