The two main causes for damage are dust and moisture. As long as your garage is moisture free - no problem. Regarding dust, the scope should come with a tube dust cover, usually a fitted plastic disc, if not buy one. Leave it on the open end of the tube when the scope is not in use. Also purchase a cloth or similar cover for the whole scope. I have a home made callico cover that goes to the floor, and I also purchased a patio heater cover with elastic trim - it fits over about 3/4 of the tube. A space blanket will also do a good job.
As long as you keep dust off the mirrors and moisture out of the tube - it will last for years.
PS - there is one other cause for damage, its called dropping - they haven't invented a cover for that yet
Clear skies
Rod
