foreign student go to Mexico with or without Mexico visa

We are Chinese students studying in U.S. A classmate of mine informed me that a year ago he used to travel to Mexico with a valid I-20 and re-entered U.S, although his F-1 visa was expired. There was no renewal needed if he came back in 30 days.

I'm planning to travel to Mexico recently. I have a valid I-20 form issued from my school but my F-1 visa was expired. I was wondering if this rule is still applicable. Please advise. Appreciate it!

Thank you very much!