When to wind it? How to set it? Where to take it for repairs? For answers to these and other watch-care questions, read on.

by Norma Buchanan

Like a car, a mechanical watch needs to be lubricated regularly to keep it running smoothly. Over time, the oil will deteriorate and friction between the movement's part will increase, causing abrasion and making the watch less accurate. In addition, the friction can create a very fine dust that will itself act as an abrasive on the watch movement parts.

Manufacturer's recommendations vary, but most range from every three to five years.

The watch is taken apart and the bracelet and case are cleaned ultrasonically and polished. The pieces of the movement are cleaned chemically and examined. Worn parts are replaced. The movement is then reassembled, lubricated and regulated. Then, if the watch is water resistant, its water resistance is tested.

If the watch is under warranty, the warranty may be invalid unless you take it to a service center authorized by the manufacturer. You can get a list of authorized repair centers from the manufacturer. If the warranty has expired, you can take it either to an authorized center or to a reputable repair shop.

It varies a great deal, but consumers can generally expect to pay upwards of $100 - sometimes a great deal upwards- for an overhaul of an uncomplicated automatic watch. As a rule, the more expensive the brand, the more expensive the overhaul.

This, too, varies by repair shop, but turnaround times for overhauls are generally measured in weeks - two or three in many instances.

No. Quartz watch movements do not need nearly as much maintenance as mechanical ones do. That's because they have far fewer moving parts -just the gears that move the hands. (A digital watch has no moving parts at all). All that most quartz watches really require is that when the case is opened for a batter change, it be cleaned of accumulated dirt. However, some expensive quartz analog watch movements should have their gear train lubricated ever eight to 10 years. For inexpensive quartz watches, this isn't worth doing.

All water resistant watches need to have their water resistance checked ever time the batter is changed or the case is opened for any other reason. That's because when the case is opened, the caskets that keep the water out of the case are dislodged. (These gaskets, or O rings, are located inside the case at the joints where the case meets the case back, crown and crystal.) For this reason it's important that when the battery in a water-resistant watch needs to be changed, the watch be taken to a repair center that has water-resistance testing equipment. In some instances, water-resistance should be checked between battery changes. If the watch is worn in the water, frequently or exposed to a lot of sweat, it should be checked at least ever two years and, if exposure to water is very frequent, ever year, says Efim Khankin, owner of Universal Watch & Jewelry Co., Birmingham, Mich.

The watch will run better if you do. "You always get better performance from a watch when it's fully wound than when it's wound down," says Daniel Fenwick, technical manager at Swatch Group (formerly SMH) Customer Service in Lancaster, Pa. It's best to wind it even if you don't intend to wear it. That will prevent the movement's lubricants from congealing.

This doesn't, of course, apply to an automatic, or self-winding watch. This type of watch should be wound initially to get it started. If the wearer is reasonably active and wears the watch for 12 to 15 hours a day, it will remain fully wound, Fenwick says.

On most mechanical watches it doesn't. On some, particularly those equipped with calendars, you should only move the hands clockwise. The manufacturer's instructions will include directions for setting.

On quartz watches, it's OK to move the hands in either direction to set them. Manufacturers point out, though, that you can eliminate the free play in minutes hand by setting it in the following way (a quartz watch, unlike a mechanical one, tends to have play in its minutes hands due to the lack of tension in the gear train): Move the minutes hand clockwise until it is a few minutes past where it is supposed to be, then move it counterclockwise back to the correct spot.

Heat and cold will affect the time-keeping ability of a quartz watch. Quartz crystals, whose extremely steady vibrations are responsible for the unrivaled accuracy of quartz watches, are cut so they perform optimally at room temperature, says Fenwick. A temperature of 100 degrees Fahrenheit will throw the timing off by about 1 second a day, as will one of 32 degrees Fahrenheit.

Extreme temperature will also affect the accuracy of a mechanical watch, but not as much as other factors (see below). One reason is that hot and cold cause the metal parts of a watch movement to expand and contract (though advances in metallurgy have made this less of a problem than in the past). Another reason is that heat and cold affect the viscosity of the oil that lubricates the movement, and thereby affect the movement's accuracy.

In a mechanical watch, wearing habits such as when the watch is wound, how long it's worn each day and what position it lies in when it is not being worn all play a critical role in determining how consistently a watch runs. Although a typical mechanical watch might gain or lose about 5 minutes a month, it's possible, by adjusting the watch to fit a wearer's regular habits, to achieve much higher accuracy than that. "The more consistent your wearing habits, the more consistent the time-telling will be," says Joseph Cerullo, technical director at the Movado Group, Lyndhurst, N.J.

None of these factors make any difference with a quartz watch. With quartz, temperature is the only variable that affects the accuracy of the movement.

In general yes, Cerullo says. All or nearly all mechanical watches manufactured today are equipped with anti-shock devices that protect the watch's balance-staff pivots - the part of the watch movement most vulnerable to damage from impact. These devices are usually effective enough to protect the watch from the shock it encounters when you hit a tennis or golf ball, for instance.

Nonetheless, there is a small change that an especially hard knock could damage not only the balance but the rotor axle, which is some automatic movements serves to secure the rotor to the watch movement. So deciding whether to wear your mechanical watch or not while playing sports is a matter of risk assessment. The odds, however, are on your side.

There is very little chance of damaging the movement of a quartz watch while playing sports -a quartz watch does not contain the delicate balance-staff pivots that make anti-shock devices necessary in mechanical watches. You can, of course, damage other parts of the watch -the crystal of instance- whether the watch is quartz or mechanical.

Don't be misled by the term "scratch resistant". It doesn't mean "scratch proof". The most scratch-resistant crystals are made of synthetic sapphire, an extremely hard mineral that measures 9 on the Mohs hardness scale (diamond, the hardest natural substance known to man, measures 10). Despite its high rating, sapphire can be abraded by some materials. Brushing against a synthetic stone surface, like those found on some furniture or walls, for example, could cause a scratch.

Also keep in mind that the more scratch-resistant a material, the more brittle it is, so scratch-resistant crystals are more likely to chip or shatter than non-scratch-resistant ones.

If it's a quartz watch, no. The position of a quartz watch has no bearing on its time-keeping ability.

A mechanical watch is a different story. Mechanical watches are regulated at the factory to run optimally on a right-handed person who will wear the watch on the outside of his or her wrist -i.e. crown down, dial up. The watch will not run as accurately in any other position, unless it is adjusted to do so. If you want to wear the watch on the inside of your wrist and have it run as well as if it were on the outside, you'll have to have it re-regulated.

A silver oxide battery will last two to three years. Lithium batteries will last 10 years or more. (They aren't interchangeable. Watches are designed to use either silver oxide or lithium batteries.)

It's unlikely you would hurt a watch doing either of these things. You would have to pull extremely hard on the stem to damage it while setting the watch. It is in theory possible to overwind a mainspring so that it breaks, but watch repairers say this rarely happens.

Pulling out the stem saves 75% to 80% of the watch's energy because the gears and hands aren't turning, says Fenwick of the Swatch Group. However, he points out, the savings is marginal when you consider that a silver oxide battery will lose 5% to 8% of its power a year just sitting unused. Another argument against trying to save battery power this way is that if the gears in the gear train sit stationary for a long time, the lubricants congeal.