Exteriors
When you store your RV outside for a long time, the exterior begins to show signs of constant exposure to the elements. Ozone in the air and ultraviolet (UV) rays from the sun start to take their toll. Ozone causes the paint to fade and makes products like rubber and vinyl dry out, crack, and deteriorate. The UV rays from the sun accelerate the aging. Before you store your RV, you need to give the exterior a thorough cleaning.
Whenever I'm washing an automobile or RV, I start from the top and work my way down. It's a good idea to clean the RV roof before putting the RV in storage. The type of roof your RV has determines the cleaner you need to use.
Wash the exterior and, if you're really motivated, wax it. Use a quality wax formulated for the type of surface your RV has. A good coat of wax protects your RV's finish the same as it does an automobile's. When you are cleaning the RV exterior, inspect all roof seams, body seams, and window seals for cracks and openings that would allow water to get in. Consult your RV dealer for sealants compatible with these materials.
Don't forget to clean the awning fabric, and let it dry completely before storing it. If you have a popup or hybrid trailer, make sure all the tenting material is clean and dry before storage.
Ideally you should try to store your RV in a covered area and on a solid surface like pavement or concrete. Avoid parking under trees and in tall grass, fields, or wooded areas. If the RV won't be parked under some type of shelter, you may want to invest in a cover. Covering your RV is a logical and cost-effective way to protect your investment.
The Chassis
Just like the exterior of the RV, tires can be damaged by UV rays from the sun. Inflate the tires to the manufacturer's recommended maximum cold pressure, and cover the tires with covers that will block out the sunlight.
Place something like a piece of wood between the ground and the tires. Frozen ground and petroleum-based surfaces, like asphalt, can damage tires. Make sure that whatever you use to block the tires is larger than the footprint of the tire.
No portion of the tire should hang over the edge of the tire block; this can cause internal damage. Chock the wheels front and rear, and if it's a motorized RV leave the parking brake off. If you are storing a popup outdoors, angle the tongue downward to assist in snow and water run-off.
Battery maintenance is an important part of winterizing. If you plan to start the unit while in storage and to periodically plug the unit into shore power, leave the batteries in the unit. Plugging it into shore power once a month for about eight hours helps keep the coach batteries topped off. (Learn more about batteries on page 34.)
At a minimum, you should check and adjust the water levels in all batteries and make sure the batteries are fully charged. A discharged battery freezes much quicker than a fully charged one. If the RV is in long-term storage, it's better to remove the batteries and store them where they will not freeze. In either case, keep the batteries fully charged when they are in storage.
If you have a motorized RV, you should fill the fuel tank prior to storage and add a fuel stabilizer. Run the engine and the generator long enough for the stabilizer to get through the entire fuel system. Change the oil and oil filter on the engine and the generator prior to storage. Acids accumulate in used oil and can corrode engine bearings, especially while sitting for a long time. Exercise the generator for at least two hours every month with at least half a rated load on it. Consult your generator owner's manual for load ratings.
Plumbing
I mentioned at the beginning of the article that the RV plumbing system is the most vulnerable to damage from plummeting temperatures. The good news is that it's easy to protect the RV water system from this threat.

Use a real carnauba paste...

Use a real carnauba paste wax before long-term storage, none of that spray-on stuff. You may need to use an electric buffer to bring out the shine.

Rubber grommets wear out and...

Rubber grommets wear out and become an ideal entry points for mice. Rodents can squeeze into openings even smaller than a quarter.

Do a thorough walk-around...

Do a thorough walk-around of your motorhome before storing it.