To prepare my cars for 6 months of winter storage I change oil and filter. I always use Texaco oil in all my cars and fill the oil filter before installing it on the car. The cars are cleaned and filled with gas. Stabilizer is added to the gasoline to keep it fresh for easy starting in the spring. I pump the tires to about 45 lbs. so they do not flat spot when sitting. Before storage, the car is driven to operating temperature to be sure the stablilized gas is run through the system. Once the car is in the correct location, I gradually pour Marvel Mystery Oil into the carburetor until the engine floods out and the internal engine parts are fogged with oil. It is then covered.
I do not have enough room to store all my vehicles, so some space is rented. If you think my car prices are high, consider the cost of renting storage. Take my 1976 Monte Carlo as a hypothetical example. I have owned the car for 30 years. Typical rental space is about $50.00 a month or $600.00 a year. Thirty years of storing the car would be $18,000.00!
All my cars are currently in winter storage. They are still for sale. You can come and look at them. If you purchase a car, I will store it for you free of charge until spring.