Last I heard was you got a 99 year lease. Only way to buy property was marry a Mexican citizen. This was about 5 years ago when a friend of a friend moved there.
Other foreigners are subject to the former standards.
Now, when it comes to owning an oil well, the government owns all of them so you can't own an oil well.
In recent years Mexico has actually adopted many tricks previously found only in American law. Used to be a man's word was a guarantee. Now, you'd best have a notarized signed statement, plus a current receipt, and have your lawyer's phone number memorized!