Right first put it up/down at least once a month if possible at least that's my mantra summer or winter!
Clean the gas strut rams (lower section) with a clean dry cloth once in a while, no oil needed, they have there own oil inside the body and given it needs to be a gas tight seal you don't want to contaminate there oil.
Make sure that the tracks that the bogies (sliders) run on is clean and grease free, maybe oil/grease the bearings of the little wheels that run in the tracks, but don't put anything in the tracks - any grease collects the dust and dirt, the wheels then skid and make for real problems!
Make sure that the two little plastic protectors are stuck in place at the front corners of the metal roof, these help stop the rubber seal sticking to the top of the metal roof and paint see here 56-787A (tape protectors)
http://www.lushprojects.com/bongopartsm ... f02.html#6