Tenant pays oil

[Michael Shadow]

Just moved in a tenant that pays his own heat. The heat is oil, how do you deal with how much oil is in the tank and how much is left when the tenant leaves? Do you top off the tank and tell them they must top off the tank before they leave? What about them stiffing you if you do that? Do you do it the way car rental places do it and say you must have at least this much left in the tank when you leave?

Any ideas or help would be appreciated.

Thanks