Loan, class

Hi everyone,

If a class is supposed to finish at 1pm, but it drags on for another fifteen minutes, would I say: The class was overrun by fifteen minutes or The lecture was overrun by fifteen minutes or would I say it in a different way?

If I take a loan and I'm willing to use my property to pay it off in case I don't have enough money, what word do I have to use? It compelely slipped my mind. I was thinking of something like: I used my car as surety. I still think that it's not the right word, because 'surety' means something different.

Thank you. I really appreciate it.