If it had no Pesach supervision at all, I have no way of knowing what might be in there and what the machinery may have been used for previously. If so, the food must be disposed of and the utensils Kashered. There are grounds to be lenient on the oven.
However, it is likely that even non-Pesach margarine is only Kitnoyos, which is significantly more lenient. I have no way of saying with certainty. I just called a friend with extensive Kashrus experience, and he too could not say with 100% certainty that no Chametz could be present.