Auto Service World
Feature   December 1, 2000   by Auto Service World

Synthetic Lubricants

Synthetic lubricants are nothing new to the aftermarket, but there are still many persistent misconceptions about synthetics.

While it is clear that synthetic lubricants offer some significant advantages–so much so that some high-performance and luxury car makers specify them as factory fill and require them for warranty service–what is not always understood is why or how they are compatible with so-called “conventional” motor oils.

Probably the most nefarious misconception about synthetic oils is that they cannot be mixed with conventional oils. Besides being patently untrue, this belief also defies logic, particularly in the face of “synthetic blend” products. It is not uncommon for a customer of a quick lube or other establishment to be told, “Once you start to use synthetic, you need to keep using it,” or “We have to flush the engine first.” This approach generally causes little more than confusion and serves as an unnecessary barrier to sales.

Additionally, there are two important points regarding synthetics and their effect on oil change intervals. In much of the literature shown to consumers, there is a statement that synthetic lubricants do not extend the drain intervals, and that the owner’s manual should always be consulted for the proper maintenance procedures and intervals. This is certainly true from a warranty perspective, but what synthetics do offer is extra insurance for the vast numbers of consumers who do not change their oil when they are supposed to. This isn’t to say that synthetic oils don’t need to be changed–though stories of the “filter change only” abound–as the additives in the lubricant do become depleted over time and failure to change the oil will accelerate engine wear and corrosion.

What makes synthetic oils so good at lubrication and protection is that the synthetic base stocks are created through chemical reactions involving base petroleum products. In these reactions, molecular structures are altered to produce highly uniform and consistent base stocks that have improved properties and higher performance. By nature, these are very stable at high temperatures–which means they don’t turn to sludge anywhere near as quickly as a conventional motor oil–and they flow more easily at extremely low temperatures.

Extended service intervals are possible in large part to the synthetic base stock’s ability to resist oxidation and to keep the effect of contaminants to a minimum.

In addition to these characteristics, synthetic oils are also able to maintain their viscosity ratings much better than mineral-based oils. This property is referred to as “shear stability” and is a way of describing how the long molecules which give an oil its thickness, so important at high temperatures, can be cut and sliced, or sheared, causing the oil to lose its viscosity.

In the old days, this was one of the main reasons that high performance cars, particularly the high-horsepower muscle cars, used relatively high viscosity oils. Despite the drag caused by pumping 20W50 oil through a system, old conventional oils would shear down so quickly that the effect was of much lighter oil anyway. Thankfully, even conventional motor oils are much more stable today and can retain their ratings for relatively long periods, but synthetics still have the upper hand.

The key points to know about synthetic oils are:

They pump easier at low temperatures

They are more stable at high temperatures

They can extend drain intervals, although warranties may not allow it

They can be mixed with conventional oils, though this dilutes their superior properties

They can reduce wear and extend the life of an engine

Most counterpeople consider synthetics to be directed at the performance market, but this need not be the case. In fact, small displacement engines in import cars–whether stock or modified–are prime candidates due to the high operating temperatures and tight clearances. In addition, any turbocharged vehicle should be considered a target market due to the high temperatures that the lubricant in these engines is exposed to, particularly where it comes into contact with the turbo bearings.

Synthetic lubricants have come a long way since they were introduced decades ago, and they are not nearly as expensive as they once were. When these two factors are combined, it adds up to a market category that has particularly strong potential.

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