Pete the Mechanic

The good folks at Pennzoil® have made an offer I can't refuse: They want to pay me to write articles about motor oil, lubrication and other automotive topics. What's in it for me? I get my picture in this publication and a regular check. Since I'm a certified mechanic with l9 years of experience, I figure it's a piece of cake.

What's in it for Pennzoil? They want to talk to mechanics and people who work behind automotive counters about the importance of motor oil in vehicle performance; and Pennzoil believes those people will be more willing to listen to a professional mechanic than to a company that makes motor oil. They've asked me to help them separate the facts from the fiction about how motor oil works, what it can do and can't do, how often it really needs to be changed and things like that. I told Pennzoil, "Well sure, alrighty then!"

What Is Motor Oil?

I decided the best place to start would be at the beginning and explain what motor oil actually is. The first motor oils were plain mineral oil which lubricated, cooled and sealed the engines of the first automobiles. But modern engines and driving habits put greater demands on a motor oil, so today's motor oils are made of lubricating oils called "base stocks" (about 80% to 90%) and additives (about l0% to 20%).

Base stocks are either "conventional," which means they're made from crude oil, or "synthetic," which means they're made from chemicals. Additives are chemicals that are dissolved in the base stock to improve its properties, characteristics or performance. By combining these ingredients in exactly the right amounts, manufacturers can make lubricants for specific uses.

About Base Stocks

Motor oils (at least the good ones) are made from paraffin-based crude oils. Paraffin-based crudes offer much greater stability at extreme operating temperatures and can be formulated to produce motor oils that are more resistant to sludge than motor oils derived from naphthenic-based crudes.

The base stocks derived from paraffin-based crude oils are very complex substances that contain thousands of different hydrocarbon compounds. When scientists select base stocks for motor oil formulation, they look for:

• Low volatility (to reduce the tendency to boil or evaporate)
• Low temperature fluidity (so the oil will flow and lubricate rapidly at start-up)
• High paraffin base (to provide stability, resistance against sludge and other chemical reactions)

Base stocks are highly processed to reduce sulfur content, remove wax and impurities and improve their resistance to deterioration in use.

About Additives

Each oil manufacturer has its own additive package. These packages are generally made of antiwear agents, detergent dispersants, rust and corrosion inhibitors and other ingredients. Antiwear agents, sometimes called extreme pressure additives, react chemically with metal surfaces to produce a protective coating in high-load areas (such as cams, valve lifters, valve-stem tips and rocker arms) where the oil film otherwise might break down.

Detergent dispersants pick up microscopic engine contaminants and chemically suspend them so they can be removed with the oil when it is changed. They are added to the oil to prevent sludge and varnish formation and are sometimes called anti-oxidants. Rust and corrosion inhibitors neutralize the acids formed by condensation and contaminants and prevent rusting and corrosive wear on engine surfaces.

Some additive packages include foam inhibitors that break down the foam produced when air is whipped into the oil by rapidly moving parts. Foaming can diminish the oil's lubricating and cooling ability, promote oxidation, reduce oil pressure, create air pockets and even cause the oil to overflow the crankcase.

Friction modifiers are another additive ingredient. They minimize friction between moving parts, which reduces engine power requirements and helps improve economy. Viscosity modifiers are also added to reduce the thinning of oil at high temperatures and the thickening of oil at lower temperatures. This allows the oil to work more effectively through a wide range of temperatures.

Since I'm writing this for Pennzoil, I ought to point out that their additive package, called Z-7, is designed to prolong engine life, and it exceeds the U.S. and import car, truck and van warranty requirements for all gasoline engines. The viscosity index improver in Pennzoil's additive package (called PennzStarTM) resists viscosity breakdown. It makes the motor oil flow rapidly so it can reach important engine parts during the critical seconds of engine start-up. It also provides excellent resistance to high-temperature and shearing-type forces.

We're The Experts

We're the automotive technicians, but today we might as well be called automotive systems analysts. We have to know a lot about a lot of different systemsÉthe oiling system being an important one. The various additive packages are one of the things that make one motor oil different from another. That's why it's important for us to know what's in them and to understand what each ingredient does. Our customers look to us as the experts, and as professionals we ought to be able to explain those differences to them. Next issue we'll tackle the nasty topic of SLUDGE! We all know how many engines have been consumed by "sludge monsters," but what really makes sludge form?

If you have any questions or comments for Pete, you can write to him at the address shown on the credits page.

Pete Sullivan is a technician and owner of Sullivan's Advanced Auto Care in Houston, Texas. He is a triple master certified by the National Institute of Automotive Service Excellence (ASE). He holds a B.S. degree in Physics and Chemistry.