Redline Automotive Accessories

Winter Storage Preparation

by Ricky Nietubicz


So you want to store your Miata for a few months. More than likely you're reading this because you live somewhere that has cold winters and you don't want to drive your Miata through them, for whatever reason- road salt, coldness, snow depth, lack of snow tires, take your pick. This article will attempt to cover the basic precautions that you should take in order to make sure your Miata makes it out of storage in great condition. I'll cover the suggestions for pre-storage prep, during-storage checks and maintenance, as well as post-storage items to get the car back on the road.

This article does NOT attempt to thoroughly cover extremely long-term storage, as this presents its own problems. All of the techniques and methods covered here are ways to minimize risk of damage to your car while in storage. Keep in mind that any sort of freak accident or unforeseen event could still happen (a mouse could find its way through all of your safeguards and eat your interior, or the engine could completely seize up for no reason) just as you could be creamed by some idiot blowing through a stoplight. The goal here, above all else, is to minimize risk.

As a final introductory note, I'd like to thank all of those who, knowingly or unknowingly, contributed to this article. My knowledge of car storage comes from storing my dad's British sports cars, some of my friends' cars, and, often, boats. Much of this article is simply a compilation of information gleaned from threads on, to get it all in one place. Thank you all.

Finding A Winter Home For Your Miata:

The first order of business is finding somewhere to store your car. This may be outside, under a carport of some kind, or in a garage, barn, or some other fully-enclosed structure, perhaps even climate controlled. Ideally, this will be your garage or other structure, on your property. Unfortunately, realities don't always permit that sort of storage, so you have to beg, borrow or rent space somewhere else. Whatever you do, I'd store the car in a fully enclosed structure, with a concrete floor, that is as secure as possible. Carport is the next best thing to keep the bird squat and UV off. Climate controlled storage is ideal, but for the cost of that, you better have a very new, very special or very expensive Miata. Browse Craigslist, ask your friends and neighbors, ask around the local Miata club, or on if you must. Consider, if possible, building yourself storage for the Miata.

If you absolutely MUST store your Miata in a barn or elsewhere without a concrete floor, make whatever floor there is as waterproof as possible. A good plastic tarp down, onto which you can drive the car, will help prevent ground moisture from rising from the ground and condensing on the car, where it will do damage. Barn-stored cars without tarps beneath them have been witnessed to have suffered more damage than cars of the same vintage that were driven through the winter, this is most likely due to the constant exposure to moisture.

It is also usually highly recommended that you invest in a good car cover that breathes. A tarp may seem like a good idea, but it's just going to hold moisture and condensation in as temperature changes, and you're going to end up with a wet, moldy, potentially rusty mess. Many sponsors sell all manner of different car covers, just remember that whatever one you buy is going to keep your baby safe, suddenly $150 or $200 doesn't sound like much, compared to new paint or hours scrubbing. This will help to keep off any UV, bird squat or dust that may otherwise accumulate on the car, and will keep those nasty critter footprints off the paint, too.

Preparing your Miata for a long Winter's nap:

Before the car goes into storage, you have to prepare it, and this involves more than just apologizing that you won’t be spending any time together for the next few months. There are some maintenance prep items that absolutely should be done. First and foremost, set a date to put it away and plan to spend some time preparing the car and properly storing it, and it’ll take some time.

Start with an oil change. Get fresh oil in the crankcase, not broken down junk. Put Sta-bil in the gas tank, then fill it up and drive it around for a good 20-30 miles to make sure that it is thoroughly mixed in and circulated through the fuel system, in the filter, the lines, all the way up to the fuel injectors. This is important if you want the car to fire when you crank it come spring.

When you pull into the driveway, thoroughly clean the car. Get all those food crumbs out from behind the seats, get all the gunk out from behind the fenders, and don’t forget the undercarriage. Give the car a good coat of wax to keep out anything that should get into the garage and through the car cover. Being more thorough counts, here, as it will make your life easier come spring. There appears to be some debate over whether to leave the windows closed or slightly cracked open all winter to allow for air circulation in the cabin. Outside, obviously close them. Inside, I think leaving them cracked slightly wouldn’t be a bad idea- IF you trust critters not to get in the car. This is a decision one must make for oneself.

Into the engine bay. Pull the plugs, disconnect the CAS to avert ignition system damage, and spray marine fogging oil into the cylinders. This is something done religiously in boat storage, some in the auto realm prefer a teaspoon of motor oil in each cylinder. It’s up to you, but I can say that in boats stored outside, the fogging oil seems to do the trick wonderfully. Spin the engine over a few times by hand to make sure the oil gets everywhere- rust on the cylinder walls can do really nasty things to your piston rings when you start it up later.

Perhaps most importantly, you’ll want to prevent critter invasions when your baby is sitting there in the garage. Mothballs can help, but you’ll have to deal with the smell in the spring, so these are likely best left around the car, in the engine bay, etc., rather than in the interior. Outsmarting critters can be tough. Good results have been reported using fabric softener dryer sheets in the interior, as well as other locations. Allegedly critters find the scent repulsive, without the disadvantage of stinking out humans as well, and they’re cheap, so worth a shot.

If your car sits in one spot all winter, you’ll likely find that the tires are flat-spotted in the spring, and they may well be flat or greatly deflated, neither of which is good for the rubber. There are many solutions to this, some better than others. First is to put “storage wheels” with junk rubber on the car and let them go to crap. Since the NA and NB have the common 4x100 bolt pattern, this may allow you to take your good tires off, saran wrap them and keep them in a nice, climate controlled spot elsewhere, while leaving junkyard steelies off of a Honda or other car to suffer through winter. A second option is to inflate the tires to around 40psi, and periodically roll the car forward and backward (every couple weeks) to prevent flat spots from developing and the tires from deflating to the point of damage. Depending what tires you run, exposure to extreme cold or simply time may necessitate replacement anyway, so just leave them on and replace in spring. Whatever you do, do NOT leave the car on jackstands. This will save your tires, at the expense of suspension bushings and the like that should not be stored with the suspension hanging.

Disconnect the battery and put it on a charger. If you have an AGM battery, make sure it is a smart charger and you don’t put the battery on concrete, as there have been reports of battery damage from sitting on concrete floors. If you don’t want to pay for the electric, get a fancy solar charger. Not a big deal, just something to think about. Remember, a “smart” or “float” charger is one that monitors battery voltage constantly, and turns on when it falls below a certain level. Once it is back up to the specified voltage, the charger shuts off again, something quite important for those with expensive batteries, as overcharging will destroy a battery very quickly. These are available from a great many sources, just make sure it’s a “smart” or “float” charger.

As final preparation, stick some rags in the intake and exhaust to prevent critters from crawling up and either getting stuck in or nesting in either. Importantly here, remember to remove these when spring rolls around. The basic goal is to make the environment as sterile as possible.

While the Miata sleeps:

You may be tempted, on one of those strangely warm days around November or December, to take the car out for a quick spin. I would highly advise against this, unless you plan to go through the entire storage routine, from start to finish, again. Furthermore, there is a routine which you should follow to return the car from storage to service, which should also be followed. All in all you’re looking at a lot of work for a quick spin, but if you want to do it, more power to you.

Remember, if you elected to roll the car back and fourth to prevent flat-spotting of tires, to actually follow through on it. If you don’t, it’s not the end of the world, you’ll just have, well, flat-spotted tires. Check periodically to make sure your critter-prevention tactics are in order, and make sure there is no unusual condensation that is sticking around anywhere. Most problems turn out to be nothing if you catch and address them early, when they start to present themselves, so check the car every couple of weeks, from end to end, top to bottom, to make sure that your precautions are in order. There are some super-anal boat owners out there who will re-fog the engines every month or so, but I don’t see this as being particularly necessary for a Miata, perhaps it is more important for racing boats with engines worth several orders of magnitude more than even a new NC.

Some people start the car every once in a while to “keep the fluids moving,” but I would advise against this, as the fluids are turning to water as condensation builds up. If you do start it, you must keep it at operating temperature for a while to boil off the water, and in the interim, they aren’t doing much protecting. More on this later.

Waking up your Miata:

Assembly may be the reverse of disassembly, but returning to service isn’t quite the reverse of putting the car into storage. There are a few things that you should do, some less obvious than others, before you fire up the car again. Carefully remove the rags, dryer sheets, mothballs, mouse traps, and whatever else you stuck in the car. Remove the plugs again, re-fog the engine, spin it over a couple times by hand. Re-connect the battery.

Change all fluids, as they have likely built up enough condensation that they aren’t going to be doing much lubrication for a long time, as you’re largely circulating water until all of it boils off. Just forget the whole thing and re-change the fluids. Better to take more precautions than less, as it is quite counter-productive to take the time to store your car to protect it from the winter, only to throw caution to the wind in the spring.

Remember that maintenance items have two intervals- mileage and time. You are supposed to change belts, hoses, fluids, bushings, filters, etc. at whichever comes first. Keep this in mind so that you don’t end up missing maintenance. Even if you don’t drive the car ever, you’ll need to change the oil, hoses, and other items at regular intervals, or you or somebody who buys the car later will have to catch up on the maintenance just as if it was a high-mileage example. While most people only keep mileage records, you’ll want to keep diligent time records as well.

Some people start the car every once in a while to “keep the fluids moving,” but I would advise against this, as the fluids are turning to water as condensation builds up. If you do start it, you must keep it at operating temperature for a while to boil off the water, and in the interim, they aren’t doing much protecting. More on this later.

Long term hibernation:

Storage of a car for a longer period of time, meaning years, is a trickier process, about which I admittedly know little. I will say only that a common problem is that owners do not keep up with maintenance, and one should assume, with no other information, that all time intervals have been missed.

Storing a car for an extremely long time presents other problems, as parts that are intended to move that don’t move can rust, corrode and otherwise seize up. Bearings can become damaged from disuse, and seals can deteriorate from a lack of fluid circulation. However, these are all topics for another article, as Miatas are much more often stored for the winter than they are for years.

Back to the Garage

13 February, 2013

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