Cold weather can be as hard on cars as it is on people. Knowing this, conscientious car owners get a major tune-up and a check of all systems before winter hits. These are the same people who read -- and follow -- their owner's manual and always park legally, even when they're late for an appointment.

There is another group of car owners -- a very large group -- who only do what they have to do to nudge their cars through another cold season. This guide is for them.

Antifreeze

You absolutely have to have antifreeze in the radiator or your engine will freeze and crack and cause you much misery and money.

Despite the absoluteness of this fact, a remarkable number of engines freeze each winter because people assume that there's some antifreeze in the radiator and that Washington winters are mild. Wrong and right. Washington winters are relatively mild but some antifreeze is not enough. The mixture needs to be half antifreeze, half water to be safe.

On a night when it's 20 degrees for you, your car hurtling along the Beltway at 50 miles per hour is experiencing a wind-chill factor of zero. With the water you've added during the year, along with normal evaporation, the mixture in your radiator could be well below the needed 50-50.

What to do:

There are several ways to approach the antifreeze task.

The best way involves flushing out with water -- numerous times -- all the old mixture, along with accumulated rust and dirt, and then putting in a new 50-50 mixture. This takes several hours, a mechanic, and upwards of $40. Car manufacturers recommend doing this every 1 to 2 years; you can probably get by doing it every 3-4 years.

The next best way: Just drain out the old fluid and put in new. This you can do yourself -- really do yourself -- because it doesn't take special tools or clothes. Just pull the plug at the bottom of the radiator and let the old fluid drain out into a pan. (Dispose of carefully. Dogs and cats like the smell and taste of antifreeze. A few gulps kills them.)

Put the plug back in and add a mixture of half antifreeze and half water up to the fill line. You save a lot of money by doing this job yourself. A gallon of antifreeze -- you may need several -- costs about $4 at the drug store and about $9 at the service station.

The last way: Add an appropriate amount of antifreeze to what's already in there, after testing the mixture to see what strength it is. You can buy an inexpensive testing gadget to do this, or you may get the service station to test the mixture for you.

Some fluid may have to be removed to make room for the antifreeze you need to add. If you don't want to pull out the plug, you can use a siphon or improvise with a turkey baster.

In a pinch -- say around mid-November when you hear on the 11 o'clock news that the temperature is plummeting -- you can forget flushing, forget draining, forget testing and just add antifreeze, as much as you can fit in, and hope for the best.

Gas

Not just any gas, but dry gas, can save you many a hairy moment in winter. Dry gas contains enough alcohol to burn off the water that gets trapped in fuel lines and gas tanks. This water makes your car hard to start. In fact, if it's cold enough, the water makes your car impossible to start because it turns to ice.

What to do:

Buy several cans at the drug store (it could be twice as much at the gas station.) Add a can each time you fill up. If that seems a bit compulsive or you have a small fuel tank, add a little each time you fill up.

When you can't get started -- it turns over but won't go -- pour most of a can into the gas tank and what's left directly into the carburetor -- right under the accordion-pleated circular object [the air filter]. You can't miss it, and it's attached by only one screw. Press accelerator to the floor once without turning the key. Then just turn the key, and you're off.

Battery

Your battery has to work twice as hard in the winter, so make sure it's up to the task. Hook it up to the machine at the service station. If it's weak get a charge. If it's near the defective range, or it's a 5-year battery and you've gotten a good 4 1/2 years out of it, consider getting a new one now.

What's a few months on a 5-year battery compared to a cold, dark night spent waiting for a jump start?

Other than age, the most common battery ailment is corrosion around the terminals, enough of it to keep juice from getting through. It doesn't take much to impede the flow of current, just a small film of white or gray powder can do it.

What to do:

Although there's an inexpensive tool available to keep the terminals clean, you can improvise with any strong-bristle brush. The point is to get off the crud inside the terminal clamps and on the interior of the battery posts. Over half the road calls received for dead batteries are not dead batteries, but corrosion around the terminals.

Also, make sure the water, preferably distilled, is up to the fill line in the battery cells. And, wear gloves around the battery. It's filled with acid.

Snow Tires

You obviously need more traction in winter. Stopping on a wet road takes four times the distance of a dry road. On ice, it takes 10 times the normal distance. Wet leaves are just as bad.

What to do:

Put snow tires on the rear wheels, unless you have front-wheel drive, then put them on the front. If you have the new all-weather tires, stay put.

Don't automatically balance the tires. It costs about $6 per wheel and it may not be worth it for the four months the snow tires will be on.

Don't automatically rotate your tires. It takes about 500 miles for a tire to feel at home where it is. Moving it around will just make it feel insecure.

If putting on snow tires unbalances the front end, your car will let you know. Then go to the expense of balancing and alignment.

Check tire pressure more frequently. Tires lose about one pound per square inch for every 10-degree drop in temperature.

Miscellany

* If you've put water, or your own window cleaner, into the windshield-washer reservoir, empty it out before it freezes into a block of ice. Buy the windshield cleaner for cars at the drug store. It contains alcohol, which prevents freezing.

* Even though it's winter, don't forget your air conditioner. If you run it for 5 minutes every few weeks, the moving parts will get exercised and lubricated, making trouble in the summer less likely.

* Winter is, of course, a good time to do an annual tune-up: Replace spark plugs, points, and condenser; adjust carburetor, choke, engine timing and compression; replace oil, oil filter and air filter; check transmission, brakes and fan belt.

Your owner's manual can provide details.