Oil 101:

Choosing the right oil... Just facts, no friction

Published in the August 2010 Issue August 2010 Feature

Royal Purple 15W-40Many people don't know how to select motor oil that will help them get optimum performance out of their truck. People often just select the oil their father used, or they may take the suggestion of a counter person at an auto parts store who may not know any more about cars than they do.

There are meaningful differences in motor oils and choosing the right one can have a major impact on how well your engine runs. Selecting the right oil is often the quickest and cheapest way to improve your truck's performance and reliability. Two components determine how well motor oil will perform in your engine. One component is the base oil, and the other is the combination of chemicals (additives packages) that are added to the base oil.


The two primary types of base oils used are mineral and synthetic. Mineral oils are by-products of refined crude oil. Refining helps reduces the impurities but leaves molecules of all shapes and sizes. Synthetic oils are manmade compounds whose molecules are all the same size and shape; consequently, synthetic oil has a less friction and performs significantly better than mineral oils.


The easiest way to select motor oil is to follow the good, better best model:

GOOD - Mineral-based (regular) motor oils. These are the cheapest and most widely available oils. They typically use standard additive packages that provide minimum levels of performance and protection.

BETTER - Synthetic motor oils. These man-made oils are more expensive that mineral-based oils but are still widely available. Their performance advantages come predominantly from the synthetic base oil used. They have a longer service life and offer some improvements in protection.

BEST - High-performance synthetic motor oils. These motor oils are the most technologically advanced oils. Although they significantly outperform mineral based or synthetic motor oils, they are about the same price as standard synthetic motor oil. They are typically only available through auto parts stores and select oil change centers. These oils primarily differ in their uses of more advanced, proprietary additive technologies.


Regardless of the base oil used, chemicals must be added to give motor oil the characteristics needed to do its job. Typical additives that may be added to base oil include detergents to reduce the formation of residue, de-foamants to deter absorption of air, anti-wear agents, antioxidants and others. In addition to the normal stuff listed above, additives need to be added to handle the soot a diesel engine produces. So, make sure you look for diesel specific oil (because it does matter).

Although additives are typically only 15 to 25 percent of the makeup of motor oil, they can impact a lubricant's performance much more than the base oil. For instance, mineral based motor oil with a very good additive package can easily outperform synthetic motor oil with a mediocre additive package.

There is no easy way for a consumer to determine the quality of motor oil's additive package. Price is often an indicator of quality since the more advanced additive technologies cost more to produce. Performance is the ultimate measure of additive package quality.


As vehicle emissions become tighter and tighter, more and more after treatments are being added. These components like Diesel Particulate Filters (DPF) are sensitive to how efficient the engine is running what is being burned. Like it or not, small amount of oil are being burned every time the piston fires. Depending on what the oil is made of, will depend on what that oils turns into when it chemically bonds with other particles. Not being a chemist, I'm not even going to try and break it down. But with the addition of after treatments, manufactures are recommending oil that has different additives. While newer engines are designed for these new additives, older engine may not. In a previous story, Cam Tech! (Diesel Tech October 2009), we briefly outlined the reduction of Zinc. In addition of Zinc levels being lowered, Dialkyldithiophosphate was also reduced. These two components help to reduce wear. In older engines, such as 12 valve Cummins, using an additive like ZDDP can help combat pre-mature wear.


Some of the biggest technological advances in lubrication are now coming through advancements in chemical additives. Royal Purple has developed lubricants that outperform both leading mineral oils and other synthetics. Their oil has been proven in numerous independent tests to dramatically reduce engine wear, increase horsepower and torque, and reduce fuel consumption and emissions. Trucks using their oils can also go further between oil changes, saving the owner time and money. Information about independent tests conducted on their products is available at www.royalpurple.com.

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