Remember to include your car on the spring fix-up list

Along with putting the lawn back in shape and sprucing up the house, remember to include the car on your spring fix-up list. Take a hard look at that car after this year's long winter. It's still running on dirty winter oil and may also be still wearing snow tires. While it may not be complaining yet, let's face it - the winter-weary spark plugs may need replacing, the cooling system need flushing, and the windshield wipers move with the smoothness of coarse sandpaper.

The Automotive Service Council states that most people tend to drive their cars until something goes wrong.

A relatively mild winter can, therefore, be harder on a car in the long run than a harsh one because it will encourage people to put off working on their car. The penalty for a neglected vehicle overcoming the winter wearies is almost always more costly than the preventive expenses.

Here are some of the things you should do:

* Check the level of the engine oil and the automatic-transmission fluid. Oil is not only a lubricant, it is a coolant as well. Clean, well-filtered oil will help your engine survive the heat.

Checking the transmission is especially vital if you are towing a trailer on a vacation trip. Most automatic transmissions share the cooling system with the engine. If you are towing a trailer, you should consider adding a transmission cooler, an inexpensive device you can have installed at most auto-service outlets.

* Pay attention to the battery. Be sure it is properly filled and fully charged. Extreme heat can cut your battery's performance. Check it often.

* Verify the proper level for the power-steering fluid and the brake fluid.

* Tire pressure is especially critical in the summer. You should check the pressure in the morning when the tires are cool. Inflate the tires to the recommended ''pounds per square inch'' pressure (32 p.s.i. is common) in order to get better fuel mileage, sharper handling, and longer tire life.

Tires may register 45 p.s.i. or more when they're hot, but don't rush to bleed off air pressure, because it may cause a blowout. Heavy loads at high speed on hot surfaces are hard on tires. To avoid failure, make sure there is plenty of tread on properly inflated tires.

While you're checking the tires for air pressure or tread wear, look for little pieces of glass, pointed stones, or any other objects that might be imbedded between the tire grooves. These can eventually cut into the rubber. Sharp fragments of sea shells can really do a job, so be extra careful in beach parking lots.

* Have the front wheels aligned. You'll get better gas mileage, less tire wear, and easier steering.

* A 50-50 mix of antifreeze and water will cool the engine more effectively than any other mixture. Coolant should be replaced once a year because the antirust additives wear out. Check it often in summer.

Never add cold water to a hot engine. After the engine has cooled down, start it up again and let it run while you add the water to the radiator; otherwise, the engine block may crack.

* Check for brittle, cracked, or soft hoses. A split could leave you stranded far from a repair shop.

* Check drive belts. They will get added abuse in the coming hot weather. Check for fraying, cracking, and proper tension.

* Pay attention to the body. Winter is hard on the finish of all automobiles, especially in areas where salt is a staple diet of the roads. Remove all corrosive agents and touch up any chipped or scratched paint to prevent rust from forming.

Once the car is in shape for summer, avoid problem situations. Don't sit in stalled traffic for long periods of time with the air conditioner running. The air conditioner puts an extra load on the engine and can add to the overheating.

As unpleasant as the thought may be, the Car Care Council recommends opening the windows and turning on the heater in order to lessen the chance of stalling. The heater provides extra circulation of coolants from the radiator.

Speed up the engine occasionally to keep the air flowing through the radiator , because the fan speed may be insufficient at idle speed when there is extreme heat. If your car begins to overheat, stop. Overheating can seriously damage the engine block and other major components. Keep a small breakdown kit in the trunk: flashlight, reflectors, jumper cables, and flares.

Hot weather can mean a heavy thirst if your car breaks down on a lonely road. Carry drinking water for such an emergency. In case of trouble on a hot day, do not try to walk for help. Auto authorities recommend staying with the car.

If you drive a late-model car equipped with a catalytic converter, avoid parking on a dry grassy area. On a very hot day the converter and the exhaust system, which get hot under normal conditions, can build up enough heat to set tall grass on fire.

''Survey after survey bears out the fact that people are complacent about the maintenance of their cars,'' says Arthur H. Nellen, president of the Car Care Council.

''We believe it is essential to remind motorists who plan a driving vacation to spend the necessary time and money to have their cars properly serviced before leaving on a highway trip.

In addition to a complete under-car inspection, a basic service should include: (1) cooling-system pressure test, (2) flushing and adding new antifreeze, (3) oil and filter change, and (4) a complete engine tuneup.

''The latter can amount to an 11 percent average improvement in gas savings over an engine that needs a tuneup. This becomes critical on 4-cylinder cars where just one misfiring spark plug will cut engine performance by more than twice as much as it would in a V-8 and increase fuel consumption by at least 25 percent.''

Preventive maintenance can pay big dividends. For more tips and literature on car care, send a stamped, self-addressed envelope to the Car Car Council, 600 Renaissance Center, Detroit, Mich. 48243.