Question: I have a 1983 240D Mercedes Benz. My warranty has run out and I want to start doing my own oil changes. I know that I can buy the manufacturer's oil at the dealer, but I am curious about other oils. Would this be appropriate? It would be cheaper.--A.D.M.
Answer: It's hard for me to imagine a Mercedes owner changing his own oil, but it's one way to get to know your car. There are many fine quality oils made under American Petroleum Institute standards. I'm sure they would protect your engine adequately as long as you follow the ratings printed on the can and make sure they conform to manufacturer's recommendations.
Q: I'm wondering if my 1984 Pontiac, with its great turbo engine, is having problems. It is driven mainly in the city, and the oil is changed every 3,000 miles. The oil-pressure gauge has failed twice. The water pump failed twice. The head gasket was replaced. Does a turbocharger cause an engine to wear out faster?--L.M.
A: The question you ask is a very important one, because today more cars are being equipped with turbochargers to boost horsepower on otherwise low-power engines.
A turbocharger forces air into the carburetor or fuel injection system, resulting in a greater amount of air/fuel mixture flowing into the cylinders of the engine. Turbochargers are typically powered by the flow of exhaust gases pushing against turbine blades, hence the name turbocharger.
The larger amount of air/fuel mixture going into the cylinders results in the engine working harder and putting out a greater amount of power than would be normal for that size engine. As a general rule, operating any machine at the peak of its capability results in accelerated wear on moving parts, such as rotating shafts and bearings.
But that's not the whole story. Usually turbochargers do not activate until you hit the accelerator pedal with a demand for a burst of power, such as when you are making a quick start or accelerating on a freeway ramp.
So, how much extra wear a turbocharger puts on an engine will depend on how much time the turbocharger is working, which depends on how the car's maker designed the turbocharger and how you drive the car.
Suppose the turbocharger is on 10% of the time, but the engine experiences double the amount of normal wear during that time. That would knock thousands of miles off the life of your engine. But that's just speculation, and probably nobody could ever really get to the bottom line of this issue.
It would help if the auto manufacturer beefed up key components in the engine to take the extra loads created by the turbo. My guess is that most car makers don't make extensive internal changes to increase engine life when they offer a turbocharger option.
Q: I have a 1974 Chevrolet Suburban with a 454-cubic-inch engine. It runs great in normal driving, but when I accelerate up a grade, the engine sputters as though it is not getting gas. I have rebuilt the carburetor and put on an electric fuel pump to no avail. Any suggestions?--C.D.V.
A: One possibility is that you have too much pressure at the mechanical pump, which is forcing gas past the carburetor needle valve and into the engine. If that's the case, you'll see the engine spewing black smoke when it sputters.
A pressure regulator would help this situation. The electrical pump should deliver about 5 to 6 pounds of pressure at the mechanical pump.
You also may have a vapor-lock situation. The pressure regulator would help in this case as well. The electric fuel pump should be mounted near the gas tank.