I'm on the startup side of the debate, I had similar problems with the SHO engine when it sat outside even covered, doesn't matter if its hot or cold, it didn't like not being started, you have to start it once a week.
The problems I saw were flat spots on the drive belts, squeeky belts, pulley idlers bearings were tighter on the spot where the tension was, so they made noise on initial start-up. Yes it goes away, so does the squeeling but the damage is already done, just loosen the tensioner upon storage or start it up regularly. The crank dampener rubber formed cracks, it didn't like the cold. But let me go internal, having polished surfaces on other steel parts even in my garage, they start to corrode within two weeks even with WD40 or grease them, I can't imagine a cylinder bore with some open valves exposed to that cold, the rings will begin to seize against the cylinder wall. I have no proof of it but looking my other steel surfaces rust they should too, have you seen pitted steel? it can't be fixed. Can you say loss of compression. It's a solid steel block, it can be ran in the cold, so I don't see the issue starting it in the cold but I do see an issue letting it sit 3-4 months hot or cold.
Lets go deeper, valve springs, do you really think they will have the same tension after being compressed 3-4 months without a heat cycle or being uncompressed? Again, I have no proof, but why take the risk especially on high performance engines which rely on spring tension to achieve high rpm's? Start the engine, you'll be fine.. Cam profiles, another polished steel surface, unless that valve cover is tightly sealed, I know mine wasn't (it was vented to air), it will begin to rust. I have no proof but you know what I'm getting at. I can't imagine the cam chain tensioner's after a long sit, can't be good. The chain rivet's, the chain pads are not immersed in oil, let them air out, you're screwed. The tbelt tensioner, just another bearing that can create a flat spot if not turned. Post #21 may ring a bell.
http://www.shoforum.com/showthread.php?t=98177
Crank seals, cam seals, they all start getting hard and brittle, they need lubrication, they need hot oil splashing on them periodically.
Power steering pump, the oil it usually so thick in the cold or long storage that when you start the car, it whines. Not being started could lead to the relief valve being stuck etc etc. Not a problem if you start it. AC compressor clutch, has to be ran to make it last. Same goes for the water pump.
Hoses, are rock hard after they sit a few days in the cold or long storage, if you accidentally compress them by hand, they will crack, not a problem if you start the car.
Fly wheel surface, thats not air tight, I can't proof it forms rust on it but I'm not going to take the risk. Pressure plate fingers, they'll start to rust as well where the TOB contacts the fingers, I have to proof but you get my point. Clutch cable, that thing feels like it is about to break when it hasn't been exercised in a while, why take the risk. Fork lever bushing, that plastic is exposed to the cold, it will begin to crack. Brass synchro's, if you leave it in gear, it will seize on the the gear snychro teeth. My old SHO 5th gear synchro actually cured its grinding after it sat for a few months, crazy. The ring gear is not totally immersed in tranny fluid, that can't be good. Not a problem if you start and run it in gear.
Fuel begins to change color and smell after a few weeks, I like to run mine low and run it out, some like to keep it full to keep the gas tank from eating itself unless they put some stabilizer. I had a plastic one, so I didn't see an issue.
What about electronics, start with the fuel pump, as a person who fixes cars constantly, fuel pumps seize up in the cold or a long storage, it happened on my daily drive just this week. They need to be run pretty much each day. What about the ECU circuitry, you really think those capacitors and components are rated at subzero windshield temps, I wouldn't trust them to be. The CCRM is another one, you think those mechanical relay's engage properly after sitting for 3-4 months in the sub zero? Then you have the cam sensor, crank sensor, coil pack, all begin to corrode, mine did, I had to take the coil off and clean the mounting surface. The o2 sensors take a lot longer to get into closed loop when they've been sitting in the cold or storage, I had to replace on because it was lagging so bad. You wouldn't notice unless you have a tweecer. I've never seen a stuck fuel injector only a failed one, but I can't imagine the storage being kind to its internal wiring, those misfires are hard to find. The alternator brushes, all have spring tension. Has anyone turned an electric motor shaft after its been sitting for a few weeks, especially when you know how easy it was to turn before you stopped using it. Its a big difference. Same with the starter brushes.
As long as you do a fresh oil change before storage, you shouldn't have to worry about moisture which causes crank cancer or oil sludge under the cap, I've never seen it on a regularly oil changed car. But you still need to start it. I'll take the risk on the moisture in the exhaust versus all the other stuff I just mentioned, I've never had an issue with rotted out mufflers or tail pipes but for the guys that run a cat, it will clog up, they need to drive it. Once you shut it down it will get moisture, nothing you can do about it, but its a risk I'm willing to take.
Suspension parts will begin to crack, i notice them cracking just from sitting, hot or cold. Same with the interior dash's & trim, luckily I've never had a leather car, perhaps cover them? CV joints, hot or cold, they will stick after sitting. Wheel bearing flat spots, I guess you could jack it up and put it on jack stands but then the bushings don't like that. Only thing to do is drive the car or exercise & **** the suspension I've worked on a boat load of cars, one's that people used to buy from auctions and they sat a long time, they have some of the weirdest problems because they sat. So many automatic transmissions fail after they've been sitting, hard shifting, late shifting, stuck solenoids, flashing Drive light, blown seals...list is endless. The cars were sold because of body damage not a trans issue, that happened because it sat. Stuck thermostats, before they realize its a blown head gasket. Weird water leaks, cracked intakes. Parts that were all recently replaced go bad once the car is started after storage. Car's don't like to sit. I always got good deals on car's that sat not knowing the problems that lie ahead, feel sorry for those that have no mechanical skills.
