Winter coming, need advice for this newbie...

My winter process since owning my Road Runner since '93;
I change the oil (10W 30) and fill the tank with fuel. I never added any stabalizer. I keep my cars in a detached, non heated garage. I keep both on a Battary Tender. I start the cars about once every three weeks or once a month. Also, I put them in gear and back out the garage and back in a couple times. Do NOT start your car is it's super freezing, I usually wait until it's been in the high 30's or 40's for a couple days. Think about how thick the oil must be when it's 5 degrees. Anyways, hope it helps.