Storing an RV, tow vehicle or toad for up to a year or more is fairly simple IF you follow some simple steps, take some basic precautions and avoid the big myth:
MYTH: Park the thing and have someone start the engine and run it for awhile every couple of weeks to "top off" batteries and "exercise" the engine.
TRUTH: Engines don't need "exercise." Starting an engine every two weeks will just cause wear and tear on the engine and transmission. You shouldn't start engine unless you're prepared to move vehicle a minimum of 30 yards both backwards and forward (what auto dealers do and they only do it every few months). Further, running an engine to "top off" batteries is as about as inefficient as you can get (in addition to causing unnecessary wear). Your starting battery (if good) will be topped off in just a few minutes. House batteries probably not at all. Doing it properly requires careful reading of a digital multimeter. Doubtful that your caretaker would want to fool with all that (might not know how to do it).
Parking can be a problem. Ideally, you'll want your rig near you. Like in the back yard so you can keep an eye on it. But you may be storing it so you can go somewhere else. Check out commercial storage places (though they're usually too expensive). Check out local farms and ranches for a covered barn or shed that you might get cheap (and the farmer might agree to be a care taker). A hail storm can really wipe things out if not under cover.
You'll want to find somewhere to park so the RV will be reasonably level. BUT, fuel, over time, will "migrate" (for lack of a better word) toward the (usually lower) front end of a parked vehicle and can saturate emission cannisters, etc. Make sure that if your fuel tank is "kind of" high, you elevate the front end a bit. (I keep my front end about 4-6" above level.)
Do NOT use hydraulic leveling jacks when putting an RV in storage. Eventually, they'll leak. Worse, after a while they'll get "stuck" in position and you'll have a hellova time when you get back.
I do not recommend wrapping the RV in one of those "bags" they sell for big $ at RV stores. Most of the ones I see are in shreds and lying on the ground. Worse, if still in place, they aren't sealed around the edges, so when you unwrap after months it's not fun when you find wasp, squirrel and bird nests.
I suggest you take care of the battery problem as follows:
The above assumes batteries are good and were fully charged when put in storage. It also assumes water level in the batteries is correct. It also assumes NOTHING in the RV is consuming battery power.
Note--particularly, the things people don't pay any attention to: TV antenna booster? Digital clock? 12V TV and Radios? (even if TV/radios and similar are turned "off," some continue to use battery power to run the memory that stores preset stations, etc.). Reefer? (again, even if off, some models continue battery power to circuit board). Make sure "Kill Switch" (if your MH has one) is in proper position. Gas valve? (If you have an automatic gas shut-off valve, it will use a LOT of battery power. Best/easiest way to avoid these "phantom" loads is to pull fuses.
Do NOT attempt to rely on your RV converter as a battery charger unless you have one of the rare RVs that actually has a user adjustable, multi-stage battery charger as part of your converter or as an independent unit. Standard RV converters will either cook your batteries or fail to charge them fully. In either case they will die. If you have old, cheap RV batteries, it's often easier (and economical) to remove them or just let them sit without charging and replace them when you return.
To make things easier on caretaker, you might invest in a digital volt meter. You can get a cheapie from Radio Shack that reads to one decimal point for $20. Far better, and every Rver needs one anyway, is a digital meter that reads voltage to two decimal points (called 3½ digits) and 20 amps of current. As long as the batteries read 12.6VDC (with nothing turned on), no charging is needed except under the "topping off" schedule above (if at all). A perfect meter for RVs is cheap ($40 Metex brand #M3800, JAMECO part# 27115) from JAMECO, 1355 Shoreway Rd., Belmont, CA 94002 (800) 831-4242. (www.jameco.com)
Water: Drain tank. It's almost impossible to completely drain most tanks, but a mostly-drained tank won't freeze enough to create a burst. Many fresh tanks have an access port on top. If you remove the plug and cover the hole with screen, left-over water will usually evaporate. Problem might be when you get back and have crud in tank if it didn't evaporate fast enough or was stored in a warm place. No big deal. It can be treated and flushed again with the "freshener" sold in RV stores.
Disconnect pump line and make sure pump doesn't have water in it (or it WILL freeze and WILL damage pump). Pump, if left with water in it, will also grow disgustingly-colored algae before you get back.
Drain water heater. Attach "blow out" plug (any RV store) with tire-filler-type air valve (called Schrader valves) to the RV's city water input. One at a time, open faucet handles, turn on compressed air and let water and crud blow out the line. (If you've never done this, you'll be amazed at what comes out of there.) Go to open next one a bit before fully closing previous faucet. Repeat. Caution: if you close everything and let air pressure run, you could blow a water line.
Sewage tanks: Dump and wash out (as best you can, but you needn't be too fastidious). Close valves. Disconnect hose (slinky) and clean it and store it. Before closing valves the final time, I suggest cleaning them thoroughly and giving them a coat of silicone grease (see later). If you don't do this, the "O" rings and seals WILL stick and you'll end up with leaks after you return and use them.
Propane: Turn it off at tank. Make sure auto-safety-shutoff isn't turned on and using electricity. You might wrap regulator in a piece of mesh or screen to keep bugs--spiders especially--from building a nest in the vent hole.
Toilet: You can fill bowl with water to keep seals lubricated. The water will evaporate in a few weeks (depending where you park). I've found that leaving the toilet empty, but carefully cleaning seal and coating it with plumbers silicone grease (any hardware store, it's used to lubricate faucet valves) works better and lasts over a year. Vaseline works, but not as well.
Shower and sink drains: The water in them will evaporate also. No problem with seals in this case, but the RV will stink when you get back. Pour an ounce of cooking oil (slowly) into them to keep the water from evaporating.
Tires and underside: Air tires to normal pressure and cover to prevent sun from rotting side walls. If good tires, no problem. If lousy, you'll need to replace them anyway when you get back. Do not completely wrap tires (or you'll end up with critters making a home in there).
Sprinkle abundant "Comet" cleanser or "Green Light" ant killer (far better) all around anything touching the ground. Ants and such won't (usually) be a bother. If you're fortunate enough to have a caretaker, the ant killer can be reapplied as needed after rains (or snow?).
Make sure holes on underside (into RV) are either plugged with stainless-steel wool (not regular steel wool) pot scrubber pieces or taped with aluminum duct tape (not just the gray tape). Either will keep (usually) rodents out.
Gas Tank: Here's where you can screw up the whole thing if you don't do it right...
Diesel systems are treated similarly. Check with auto store or, better yet, with a "John Deere" store for proper chemical. (I have done all this and left RV in storage for over 2 years and it started right up--but see below.)
ENGINE: Let's assume some things. Before you put your RV in storage, you'll have done the above, had transmission serviced (including change of fluid), lubed and changed oil and filter.
• It isn't necessary to remove spark plugs and squirt oil in each cylinder then reinsert plugs unless the RV will be in storage for more than a year.
• If it will be in storage more than six months, you should get a pint of "Marvel Mystery Oil" and when you run the engine the last time, at idle, air cleaner removed, slowly pour oil into main (front) carb throttle bores (or throttle body air inlet on fuel injection systems). When down to about ½ a pint, pour faster to stall engine out. Do not start it again. Your cylinders and upper valve train will be nicely coated with preservative oil.
• There's little to do in the engine compartment. Cover air cleaner with screen or aluminum foil. Taped with aluminum duct tape to keep critters from getting into the filter element. Some people spread moth balls around, but I can't see that it does much good. If you park in a rodent-infested area they may very well eat wire insulation, hoses, etc., anyway.
Removing from storage:
Answers to some questions:
This article courtesy Phrannie.org.