Mr Fire, No, You cannot work 40 hrs on F1 visa during school year. You can either choose to work 20 hrs for your co-op or 20 hours on campus. You cannot combine the two at all. Thatz the law. However, I dont think you are going to have any significant problem even if you did. The school always warns you if they found it. So be careful and do wtever it takes to finish your studies.