Things to check to keep your car running well

Sensible driving is essential to safety. But so is maintaining a vehicle in tiptop shape all year long, especially in winter.

If you find your door lock is frozen some morning, heat the key with your breath or a match. You also can get a defroster in a spray can.

Here are a few pointers about conscientious car maintenance designed to improve a car's safety and performance: Automatic choke

When you start the engine, the choke plate at the top of the carburetor should close. As the engine warms up, the plate opens. On colder days, the plate takes longer to open. If the choke is not working correctly, the engine may not start or may stop during a burst of speed when you pull into traffic.

Check the choke by removing the air cleaner top to see a small plate on the top of the carburetor.

Ask someone to press the accelerator pedal to the floor. After releasing the pedal, see if the plate (choke) snaps shut. Now start the engine. Watch the choke plate. When the engine starts, the choke plate should open slightly. But as the engine warms up to operating temperature, the choke plate should open completely.

If the choke plate doesn't close all the way at the start, or opens gradually , or all the way, have a garage check it. Battery

The American Automobile Association reports that battery and electrical system failures are responsible for about half of all car breakdowns.

Clearly, you need a hot battery for cold winter starts.

Check under each cap to see if the fluid covers the plates and the terminals are not corroded. Ordinary baking soda and water will remove any corrosive buildup.

Inspect the clamps and cables for cracks and looseness. Almost any garage or car-service center will give you a free battery-power check.

Some batteries are maintenance-free, of course. You may have to replace the battery. Coolant

Check out the water-cooling system before winter.

All water-cooled engines from the factory have antifreeze, which protects both the engine and the radiator down to 34 degrees below zero. The 50 percent ethylene glycol and water solution is a better coolant than just plain water. If your car has a coolant-recovery system, check the fluid-level marks in the translucent container to one side of the radiator.

The coolant can last as long as five years since no air can get into the cooling system.

Replace the coolant in pressurized systems without a recovery reservoir every two years. But checking the cooling system is a must. Remove the pressure cap (not when the engine is hot), allow the engine to idle, and inspect the circulating coolant passing the filler neck. Signs of rust or sediment call for replacement of the coolant. Before draining the system, see if the radiator and heater hoses are mushy or brittle. If so, replace them.

Does the radiator cap fit tightly, respond smoothly to finger pressure, and have a soft rubber seal. It should.

Also, a stuck thermostat will overheat the engine. Your car won't run at the proper operating temperature, and this will result in fouled spark plugs, carbon buildup, low gas mileage, and engine damage.

Any service station will give you a hydrometer check, replace the thermostat, and put in new radiator coolant.

This is also a good time to look at the drive belts. A faulty or broken fan belt cripples a car's cooling system and undercharges the battery. A broken power steering belt reduces your ability to control direction. Have a service attendant check also for proper belt tension. Vision

Know how the defroster, temperature controls, and car heater should be set. Windshield washers and wipers require special attention. Clear the lines for good flow, fill the container with a nonfreezing solution, and replace worn blades.

Keep all windows clear of ice and snow. Trying to see through peep holes is dangerous. Keep the headlights and taillights clean - a continuous chore in winter. Exhaust

Never warm up your car in an enclosed garage or run the engine if the car is stalled in a snowbank unless you roll down the windows for ventilation. Also, if the engine sounds loud or rumbles, you could have holes or cracks in the exhaust system. Have a professional service attendant inspect the car.

While your car is in a service garage you might want to have other inspections made as well. If you haven't had a completely engine tuneup, then now is the time to do it. A complete job involves going over your car's electrical and ignition system with air and gas filter replacements.

Avoid being caught with a dead car late on a cold winter night because of badly worn or damaged distributor-cap terminals or spark plugs. Tires

Tire-tread depth is what counts because the treads bite the snow and ice. Never hold on to tires with less than one-sixteenth of an inch in tread depth, abnormal wear on one side, or tires which were damaged by striking the curb.

If driving on snow is the rule rather than the exception and you have a rear-drive car, put snow tires on the front as well. You'll find steering a whole lot better.

But remember, don't lull yourself into believing you can stop quicker and shorter with snow tires on ice. The National Highway Traffic Safety Administration (NHTSA) warns: ''Conventional snow tires (without studs) offer no advantage over regular tires in stopping on ice. But studded rear tires reduce braking distance on ice by 20 percent compared with regular.''

Check the law regarding studded tires in your state - and other states, too, if you travel.

''As far as radial tires are concerned,'' says NHTSA, ''they offer no advantage over regular tires when driving on ice. And the traction performance in snow varies.''

The Tire Industry Safety Council debunks the myth of lowering tire pressure for increased traction on snow and ice. ''On the contrary, deflating your tires decreases traction and makes handling more difficult,'' it asserts. What to carry

Winter motorists should carry booster cables, a folding-handle shovel, tow strap or chain, window scraper, flares, traction mat, sand or rock salt, tire chains, a roll of paper towels, flashlight, blanket, and even some candles so as to keep the car warm if you ever have to wait for road assistance.