Tech Stuff

Refining your engine oil selection: Oil is oil, right? Wrong!

About the author: Weber is president of Virginia-based Write Stuff. He is an award-winning freelance automotive and technical writer and photographer with over two decades of journalism experience. He is an ASE-certified Master Automobile Technician, and has worked on automobiles, trucks and small engines. He is a member of the Society of Automotive Engineers (SAE) and numerous other automotive trade associations. He has worked as an auto service technician, a shop manager and a regional manager for an automotive service franchise operation.

Carmakers are getting picky. Once upon a time there was one universal type of antifreeze. Once upon a time, there were two types of automatic transmission fluid. Once upon a time, there were just a few common grades of motor oil. Times have changed.

Think using the wrong oil in today’s engines is “not a big deal?” Think again! The incorrect engine oil selection can not only lead to premature wear and tear of internal engine components, but it can also cause major drivability problems.

Of course, we all know that using the wrong oil will not result in immediate catastrophic failure, but over time it can take its toll.

AutoInc, the journal of the Automotive Service Association, reported that:

Sometimes the wrong motor oil gets used in a vehicle, and despite the imaginative illustration that pictures an engine immediately seizing up, the likelihood of that is small. But, even though an engine doesn’t completely seize up from using the wrong motor oil doesn’t mean damage doesn’t occur. “If a Corvette was given starburst oil because someone didn’t read to know it needed a special oil, there wouldn’t be immediate failure,” said [Mark Ferner, lead product engineer, Pennzoil Research and Development]. “But over time, problems would likely develop.”

According to Ferner, small mistakes may lead to big damage. “The right oil will have the right balance of base oil and additives for a given engine. If an oil lacks the right components or the right balance, bad things may happen. Depending on which additive is missing, you can have metal-on-metal contact in the valve train. A motor oil lacking certain antioxidants could see heat damage since local hot spots in the engine spike to 400-600 degrees F. Over time this buildup of varnish can keep parts from moving properly.”

European car makers have a variety of special oil requirements, so be sure to reference the specification in the service manual or owner’s manual to verify the use of the correct oil.
<p>European car makers have a variety of special oil requirements, so be sure to reference the specification in the service manual or owner’s manual to verify the use of the correct oil.</p>

But just as automakers have been moving toward specific coolants and automatic transmission fluids, they are starting to demand specific oils for their engines.

European automakers started steering away form the universal, one-size-fits-all concept in the 1990s.

For example, BMW, with the introduction of the 1999 3-Series (which the company calls its E46 series), introduced extended oil changes of up to 15,000 miles (or once a year). At the same time, the company introduced BMW High Performance Synthetic Oil SAE 5W-30.

Castrol was the first to produce a compatible oil for the American market.

According to Liqui Moly, “Oil must now be capable of much more than just lubricating and cooling: It must function even at elevated temperatures and pressures; it must clean the engine from combustion residue, grit, acids, water and fuel particles; it must protect the engine from corrosion and keep its density. Modern engine oils are high-tech liquids designed specifically for use in certain car models, practically tailor-made replacement parts.” As a similar example, not every engine can use the same spark plug.

What happened to Audi about 10 years ago set the stage. Audi and Volkswagen 1.8L turbo engines suffered from an internal build up of sludge. The oil almost turned tar-like causing severe engine damage. The carmaker narrowed the problem to incompatible engine oils that did not meet its specifications.

As a result of a class action lawsuit, the carmakers extended the warranty to 10 years or 120,000 miles.

These were not inferior oils or off-brands, but well known brands meeting API and SAE specifications. Volkswagen and Audi have a special oil requirement and the extended warranty was only valid if car owners used the proper oil meeting the VW502.00 spec. And it must be synthetic oil.

Recently, General Motors has established a new engine oil standard known as dexos1 (yes, with a lower case “d”).

According to the GM dexos information center, the company manufactures cars and trucks in 34 countries and sells them in over 140 countries. These vehicles contain an array of more than 20 different engine sizes. To function well and to last a long time, these increasingly high-performance engines need consistently high-quality oil, and that quality and uniformity needs to be available anywhere in the world.

GM dexos is a proprietary, global engine oil specification designed to meet the requirements of GM vehicles worldwide.

According to the dexos information center, the dexos specification “...has gone through an extensive developmental and testing process. It requires a number of proprietary tests that are not included in current industry standards and sets performance criteria at a level that exceeds many current standards. The result is a high performance fluid providing significant wear protection, improved piston cleanliness, a reduction in volatility and oil consumption, enhanced aeration control for improved fuel efficiency, and better oxidation properties.” The name dexos is an exclusive trademark of General Motors. Only those oils displaying the dexos trademark and icon on the front label have been certified and licensed by GM as meeting the demanding performance requirements and stringent quality standards of the dexos specification. The license holder is required to display its number on the product package.

GM claims that “...using substandard oil can affect engine performance and, in the worst case scenario, may damage or harm the engine. Unlicensed products have not gone through GM’s rigorous testing process, are not monitored for quality, and are not approved or recommended for use in GM vehicles. Unlicensed product quality and suitability for GM vehicles cannot be guaranteed and, therefore, use of unlicensed products may result in lower levels of performance and could cause engine damage that may not be covered under warranty.”

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