W123 Storage procedure.

[Shern]

i'm heading to out of town for about 30 days.
The 240d will not be driven during that time.

Is there anything I should do to her while she waits?
Doesn't seem like enough time to warrant disconnecting the battery or adding anything to the fuel, but I'd rather be thorough and find out.

And in the interest of posterity (future search strings), is there a safe upper limit on how long these diesels can be parked without being driven?