Self-service: more than just pumping gas

Has your car lost a good friend - the service-station man who used to fill the gas tank, check the oil, and wash the windshield? A good worker also would keep the battery from going dry, show you where the fan belt was cracked and worn, and tell you if the water hose was about to let go. He'd even cast an eye at the tires and add air if he thought it was required.

Now if you pump your own gas, the extras are up to you. Carmakers complain that too many motorists pay scant attention to what goes on under the hood, and their cars are the worse for it.

What you may need is a mini-course in auto anatomy. To start, you can take the owner's manual out of the glovebox and read it carefully. Auto manuals are not always written for the uninitiated, but you can at least find out where the dipstick is.

Nothing is guaranteed to ruin a car quicker than letting it get too low on oil. The older the car, the more frequently you should check the dipstick. It's a good thing, in fact, to check the oil yourself, even if you have just had the oil changed by a mechanic.

When you take a car in for repair, make sure all the scheduled work has actually been done.

I once took my car to a trusted mechanic for an oil change and some other minor work. About a month later, the low-oil light suddenly came on, and I discovered that the car was almost out of oil. The mechanic had done the other work but had forgotten the oil change.

Also, be sure to check those bills. Ask questions. If I had checked the bill, I would have seen that an oil change was not listed.

Incidentally, your car manual will tell you what kind of oil should be put into the car. You can buy oil at discount stores and add it yourself if you wish. In areas where gasoline stations are mostly self-serve, you're going to have to add it yourself anyway.

Remember that it is important to see that it's done. Running out of fuel isn't half as serious a problem as running out of oil.

If you have an older car, check the radiator water sometimes before you start up; in other words, before the water gets hot. Take a look at the water hose. If the hose is cracked and worn, have it replaced. It is disconcerting to have a cloud of steam suddenly erupt from under the hood.

Should the car start to steam, however, do not immediately add cold water because it can crack the engine block. No matter how hurried you may be, first let the engine cool down.

Then check for a radiator leak, cracked hose, leaky hose coupling, or stuck thermostat before you go much further. And be sure to check the antifreeze protection of the radiator if you add more water.

Don't ignore puddles or damp places underneath the car. Find out what causes them. If it is oil, it may mean only that the drain nut wasn't properly tightened after the oil was changed. Go back and have it checked. If that's all right, then find out what is causing the oil loss. Sometimes it pays to get two opinions.

It's always advisable to keep a fire extinguisher in a car, but don't keep it in the trunk. You want it readily available in case of need.

The car manual will tell you how much air should be in the tires. The figures may also be inside the glove box. Follow the recommendations. A good tire gauge is inexpensive and easy to use.

You also might learn to judge the appearance of the tires. Find out how to tell if the tires require rotating or if it is time to have the wheels of your car realigned. A poor tire is bad economy and can lead to problems on the roadway.

You might want to attend an adult-education class for more details on how to maintain your car. Classes are often given by high schools and local colleges. The classes may not turn you into a mechanic, but you will learn the anatomy of cars in general - and your car in particular. The information helps in buying cars, too.

When it comes to car upkeep, I prefer places where I can talk to the mechanic who will do the work. I have found that good mechanics will often welcome direct contact with a motorist who listens intelligently. You can't always do that, of course, especially at new-car dealerships.

Along with taking the course in car care, a good book on car anatomy is a handy acquisition for future reference.

My own favorite is ''Auto Repair by Dummies,'' by Deanna Sclar (McGraw-Hill). If there are no classes available in your town, one can self-instruct from this humor-coated fount of information on everything you ever wanted to know about cars. At the same time, the book doesn't patronize. However, it has been in print for quite a while, and the parts and labor prices are pre-inflation.

Even if you have never held a wrench, and you've failed in shop or arts and crafts, take heart. You can still be your car's best friend.