Motor Oil: Broken or Worn Out?

Motor Oil: Broken or Worn Out?

The only protection that mechanical parts have
for cleaning, cooling, sealing and lubricating
inside the engine is a thin film of motor oil

By Steve Ford - The Car GuyŽ

You have never been told that your car's motor oil is broken, yet you're always being told to change it -- why?

It's not news to hear that motor oil is the "life blood" of your car's engine. No one disputes that point. The area where I observe the most confusion is the when and why of changing motor oil. Today I want to address one of the most typically asked questions so that you can make your own informed decision on the topic of oil changes.

The function of motor oil is really pretty simple. I'll never forget the way my Granada Hills High School auto shop teacher, Mr. Mills, explained it for our final test preparation, "The four jobs of motor oil are to clean, cool, seal and lubricate." Funny, I thought that oil was just to lubricate. That's where this topic gets a bit more complicated.

Now, if you want the short version of the WHEN of today's topic, here's the answer: The perennial oil and filter change interval recommendation that you keep hearing of "every 3,000 miles" is correct. Naturally, this is earlier than necessary for many newer cars that are running full synthetics. And the majority of newer-car factory recommendations are for oil-change intervals of often as much as 7,500 miles, or more.

What no one can dispute is that traveling as few as 3,000 or 4,000 miles on the majority of cars and trucks between oil changes is simply keeping on the "good" side when it comes to auto maintenance. The irony is that since oil doesn't signal its failure by suddenly breaking, many motorists will drive up to as far as 10,000 miles before changing the oil because nothing seems to be going wrong. That is an expensive decision.

If you want the foundation for that answer so that you can agree with the proposal of changing motor oil on the earlier side of the mileage intervals for yourself, please read on.

Q: HOW DOES MOTOR OIL ACTUALLY "WEAR OUT?"

A: It is sometimes difficult to perceive the wear that motor oil undergoes during the thousands of miles that we travel between changes. Yet, when you take a closer look at the composition of motor oil it becomes more apparent.

In its essential form, motor oil is a significantly refined and enhanced form of petroleum. Translating the word petroleum back to its roots in Latin reveals that "petra" means rock, and "oleum" means oil. So, we are really only talking about rock oil here. Think about it, "rock oil" insulating and protecting vital metal surfaces in your engine from scuffing and wear as you travel on that open stretch of highway.

Consider the fact that even if oil refineries removed all of the abrasive particles, acids, water and other contaminants from the original crude oil, in its basic form the substance would develop into sludge and lose a significant portion of its lubricating qualities after only several hundred miles of typical commuter driving.

Your own car's motor oil actually gets dirty after you drive several hundred miles. Here's what makes it possible for you to enjoy driving as much as 3,000, 3,500 or perhaps as much as 4,000 miles before the oil in your particular engine starts to turn back to "rock oil" again: Those smart motor oil chemists developed unique oil-booster products that help extend the life and enhance the performance of petroleum. These oil-booster products are called "additives."

After conducting an extensive filtering process to make oil clean enough to flow between the tight clearances of mechanical parts in today's precision engines, motor oil companies blend in the various additives into the motor oil to enhance its longevity, lubricating qualities and durability. The following are just a sampling of the additives that are blended into today's premium motor oils:

o DETERGENTS: Help clean engine mechanical parts and surfaces to prevent buildup of sludge, varnish, as well as neutralize harmful acids.

o DISPERSANT ADDITIVES: A good analogy to help explain dispersant additives is a comparison with your laundry: If you put stain remover on one piece of clothing, you don't want it to simply wash onto another piece of clothing -- you want it to remain suspended and drained out with the detergent! So, in you car's motor oil "dispersant" additives help keep contaminants, such as sludge or acids from bonding together and depositing (staining) on metal surfaces. (They disperse/suspend bad stuff until your next oil change.)

o VISCOSITY ADDITIVES: "Viscosity" refers to the flow rate or thickness of the oil, and is the term that is also sometimes called the "weight" of motor oil. The viscosity additives help stabilize and maintain the optimum thickness of oil over a broader range of temperatures than the natural petroleum base stock would otherwise deliver.

o ANTI-SCUFF/FRICTION MODIFIERS: These commonly synthetic and chemical oil boosters help strengthen oil's lubrication and protective film qualities. Anti-scuff additives are particularly important in helping prevent the breakdown of motor oil during hot driving.

o CORROSION INHIBITORS: Anti-corrosion additives help prevent rust and other chemical reactions from water condensation and acids on iron, aluminum and steel surfaces throughout the engine.

Those are just a few of the many elements that oil companies blend into motor oils to literally boost the endurance of the original oil product. Here's the key point: Each of these additives only complement the lubrication properties of motor oil to help it clean, cool and seal. Yet, each one of these additives can only help oil for a limited period: "detergent" additives eventually get used up; "dispersant" additives can only disperse and contaminants for a limited time period, and so on.

Eventually, that proud and modern motor oil loses those "high tech" additives as their properties wear out. Then that motor oil once again becomes simply rock oil -- and each mile you drive starts silently trimming mileage and performance from your engine.

Remember that after those precious motor oil "additives" wear out, the lubricating qualities that protect your engine begin to steadily diminish -- and before you know it the liquid in your powerplant has returned to being "rock oil".

Copyright 1995 - 2010 - Entire Contents - Steve Ford, The Car Guy - Est. 1983
Ž The Car Guy - 1983 CA; Interstate Registrations 1985; 1997 - Trademark Registered: United States Patent and Trademark Office