storing my 89 560 sel for the winter

Fuel stabilizer on a fresh tank of premium gas. A full tank allows for less evaporation in my experience. Other than that, putting it on blocks under the suspension not the frame will help out the tires and keep the suspension pieces close to where they want to be. You don't want to let the suspension droop for extended periods as it will stretch the rubber bits. Of course a good bath inside and out helps with a couple pieces of regular cheapo (not mesquite or quick start) charcoal in a brown bag under the seat will help keep any mildew smells away. Cover it if you can and don't let the kiddos stack crap on it.

Yeah, forgot about the battery. I'd just disconnect the negative terminal. I had a friend that lost his garage, Toyota trail truck, new Z06 Corvette, Harley, and full craftsman tool storage plus a very nice fitness room upstairs due to a faulty factory supplied battery tender on the Harley. So I won't recommend any type of tender setup. He is still dealing with the insurance on that from a year ago. Thankfully it was a detached garage so it didn't burn up his house with his family inside. He was gone to Afghanistan when it happened. Honestly just disconnecting it should be good enough if it is a good battery. Maybe put it on a trickle charge a few hours before you go to restart it but again, be cautious..

See that story here: http://www.ttora.com/forum/showthread.php?t=183960