Gasoline and oil are just commodities to most people. They know their cars need gasoline on which to run. They also know that if something happens to the oil it spells big trouble. Beyond that they rarely give much thought to gasoline and oil. This is a mistake. Gasoline and oil are vital to your car's health and operating economy. You need to know more about them.


FUEL
The fuel in your car's tank is what makes it all happen. Fortunately, this subject is relatively simple and clear-cut, at least compared to some car care subjects. There are, none-the-less, a few things the average motorist needs to know about fuel.

Choosing the right type of fuel.
Basically, there are only two types of fuel: unleaded gasoline and diesel. If your car has a diesel engine, the choice is easy: You cannot use anything but diesel fuel. Prior to 1971, all cars sold in America (except a few imported diesels) were designed to run on leaded gasoline. Leaded gasoline came in a wide variety of octane ratings, from 87 octane regular all the way up to super-premiums with octane ratings of nearly 100 (in some cases even higher). Since 1971, however, lead has been gradually phased out due to environmental concerns and now it is impossible to buy retail leaded gasoline.

What are owners of pre-1971 cars supposed to do? Fortunately, government restrictions apply only to lead at the pump. It is still perfectly legal to buy lead additives that can be added to unleaded gasoline to boost octane ratings. These additives are available from auto supply stores.

Many classic automobile owners find that lead is unnecessary and only hastens the deterioriation of the inner-workings of the car. But, Expert opinion is divided. It is probably not a good idea to run a car designed for leaded fuel on unleaded fuel alone. Pre-1971 engines need the the small amounts of lead in leaded gasoline in order to lubricate their valves. (The valves on newer cars are designed to do without.)

There is an even more serious problem with pre-1971 cars. Many of them were built with rubber fuel lines. The danger is that the additives used in modern unleaded gasolines can react chemically with the rubber in these older fuel lines causing them to rupture. An increasing number of engine fires involving older cars testifies to the serious nature of this problem, and the situation can only worsen with leaded gasoline withdrawn from the market. So, if you have an older car it would probably be wise to have your mechanic check your car's fuel lines and, if they are rubber, replace them with metal ones. If that is not feasible for cost or other reasons, plan to replace the rubber fuel lines every two or three years. This shouldn't cost much and, in any case, is far cheaper than having your car destroyed by fire.

Unleaded Gasoline.
Most cars on the road today use unleaded gasoline. This generally comes in two grades: regular (87-89 octane) and premium (90-93 octane).

How much octane does your car need? You are the best judge of that. You should try different octane ratings until you find the lowest rating that provides good engine performance. If the octane rating is too low, you will experience engine "knock" and, possibly, "dieseling" or "run-on" (where your engine sputters on for a few seconds after you turn off the ignition). If either of these conditions exist, up the octane a notch with your next tankful.

You may have to experiment around a little with different brands of gasoline. While there are many motorists who devoutly believe that all brands of gasoline are alike, it isn't necessarily so. The basic refining techniques are the same, of course, but when you buy a tankful of unleaded, you are buying more than just gasoline.

All gasolines are a blend of gasoline and the various additives that the refiner saw fit to throw into the brew. These additives are designed to do such things as boost octane, suppress engine knock and counteract water. Different brands of gasoline may--and, indeed, probably do--contain different additives. Your car may run poorly on one brand of 87 octane and like a grand prix race car on the brand of 87 octane for sale across the street.

There is no point, however, in paying for a higher octane fuel than your engine requires for smooth running. Enough is, literally, enough. Anything above the minimum requirement just goes out the tailpipe. On the other hand, prolonged used of an octane that is too low can cause serious engine damage.

Never use leaded gasoline in a car equipped with a catalytic converter (a category that includes most cars built since 1975). The lead in leaded gasoline can destroy the catalytic element leading to expensive repairs and, in some cases, even fires.

Facts about fuels containing alcohol.
Recently, still another category of fuel, known as "blended" fuel," has become available in some parts of the United States and Canada. This type of fuel contains a mixture of gasoline and some form of alcohol: ethanol (ethyl or grain alcohol), methanol (methyl or wood alcohol) and cosolvents. Fuels containing less than 10% ethanol or less than 5% methanol are considered safe by most manufacturers for cars designed to run on unleaded gasoline. It is unwise, however, to use any fuel not recommended by the manufacturer of your car. Check your owner's manual or with a local dealer handling your make.

(Note: Fuels containing alcohol can cause damage to your car's paint. So, if you use these types of fuel, be especially careful to avoid spilling fuel during refueling.)


ENGINE OIL
Most car owners are fairly casual about engine oil. They are casual about checking it, casual about selecting it and casual about changing it. This attitude has been reinforced by the manufacturers and by the oil companies who know that American drivers do not like to fuss with their cars. The experts--those who drive their cars 100,000 miles or more and those who work on cars--have a different story. There is one thing they agree on: The biggest key to long, trouble-free engine life is meticulous attention to engine oil.

How oil affects engine life.
In order to cater to the casual approach of modern motorists, the auto manufacturers have gradually extended recommended oil change intervals to where they are now in the 7,000-8,000 mile range on most new cars under normal driving conditions. This is double the recommendation of 20 years ago. In addition, some of the oil companies are advertising special long-life oils that will supposedly last for 10,000 miles or more.

Don't believe it.
It is not that anyone is lying to you. Modern oils are marvelous and retain their chemical integrity far longer than they used to. They just aren't telling you the whole story. The issue is not the oil, but, rather, what is in the oil. It is important to understand that the oil in your engine serves two purposes.

First, the oil in your engine is there to lubricate the basic moving parts of your engine, enabling those parts to move with less friction and, therefore, with less wear and heat build-up. The second purpose of the engine oil is to collect foreign matter--dirt, grime, etc.--that gets sucked into your engine via the air intake. The air cleaner on your engine traps most of this--provided you properly maintain your air cleaner (and that's another subject!)--but some of it inevitably gets through. The longer the oil stays in your engine, the dirtier it gets and, no matter how good the oil, it can only hold a certain amount of contaminants before it gets overloaded. When that happens, damage to your engine's vital parts begins.

When to change the oil in a new car.
New cars are generally delivered with a special low-viscosity oil called "break-in" oil. This oil is intended to provide super-low friction during the critical new-car break-in period. It is not intended to be used on a long-term basis and can lead to serious engine damage if not changed at the proper time. Most manufacturers recommend changing the break-in oil no later than the first 1,000 miles. Many experts recommend changing it after the first 500-600 miles.

When to change the oil--normal conditions.
Many experts recommend changing oil every 2,000-3,000 miles. Others say that if you take the manufacturer's recommendation listed in your owner's manual and divide it by half, you are probably in the ballpark. The point is, change it regularly and change it often.

When to change the oil--special conditions.
Under certain types of driving or with certain types of engines, oil changes should be done more often than usual. Engines fitted with turbo-chargers are operating under unusually high heat and stress and need all the help they can get. Increasing the frequency of oil changes can be a big plus.

Diesel engines are another case. This type of engine, although no longer popular, can be rugged and economical when properly cared for. A diesel is not, however, as "forgiving" as a gasoine engine. Fanatical attention to oil change intervals is essential for long-term enjoyment of a diesel engine.

All engines require more frequent oil changes under special driving conditions. Some of these special conditions are:

• Driving in dusty areas.
• Trailer towing.
• High percentage of urban driving.
• Extremely low annual mileage.
  
• The latter two categories deserve further explanation. Many drivers use their cars exclusively around town in stop-and-go driving situations where the typical trip is 5 miles or less. Under these conditions, your engine barely has time to warm up--especially in winter weather--and the wear and tear on engine parts is greatly accelerated. More frequent oil changes are a must. Moreover, many cars--particularly with older drivers--are used only a few thousand miles per year. Engine oil deteriorates due to age as well as mileage and any car should have its oil changed at least every six months, regardless of the number of miles driven.