Choosing An Engine Oil

All engine oils are not the same, despite statements by well-meaning but not well-informed "experts" -- and the differences in engine oils can affect the life and performance of your engine. Specifically, there is a wide range of quality and performance differences among the base stocks and additives used for blending mineral, synthetic and semi-synthetic oils. Each formulation varies in its ability to prevent or lessen a variety of adverse operating conditions, such as foaming, deposit formation, difficult starting or pumping at low temperatures, contaminant drop-out, and catalyst poisoning to name just a few. The end result is a wide and often confusing array of engine oil choices, whose formulations are often changed for better performance or price competition.

With such differences among oil formulations and engine specifications, the challenge for consumers is to choose the best oil for their kind of driving and climate. While price is important, it should not be the primary factor, considering that good oil is the engine’s life blood and life insurance. The need is to distinguish between oils of better or poorer performance properties in relation to the desires of the auto owner.

Modern engines of today have made great advancements in providing better performance and efficiency. In doing so, these engines have also placed greater demands on the quality of engine oils. In response, engine and engine oil manufacturers have generated a number of detailed oil specifications. Many oils meet the specifications -- some don't. More importantly, there are significant differences among those that do meet specifications.

IOM's information shows that engine oil properties and performance can vary widely. For example, some oil companies produce what has been called “fighting grade" oil that might just meet certain critical specifications. Some also make a "premium grade" product that passes the specifications relatively easily. The first is just good enough; the other is very good. Differences in brand names and prices on the container are clear, but differences in quality of the oil inside are not.

The purpose of VoxPop® is to help make the automobile owner’s choices clearer by providing unbiased, independent information and data. We can't tell you what oil is best for you to use, but we can provide the information for you to easily compare oils and make the best choice for your own needs.

It is also good to be aware that the properties of a given brand of oil may change from time to time as a result of advancements in research and development -- or of a need by the manufacturer to change its competitive position in the market. Formulations change, ingredients within the formulation change, and new products become available. In addition, there can be inconsistencies in the blending, packaging, and shipping process. The VoxPop® Report shows how a chosen brand of oil compares to all other oils collected from the market of the same category. By including different samples of the same oil, it also shows how consistently the oil is made. Keep in mind that a given oil’s formulation may change with time. It is a good idea to reorder reports periodically to make sure you are keeping up with the changes.

Some oil properties are more important to the life of your engine than others. Those properties considered to be among the more critical are identified below and discussed in greater detail in our online Glossary of Engine Oil Terms.

Viscosity Starting Viscosity (Startability) Pumping Viscosity (Pumpability) Gellation Index (Gelling Tendency) Operating Viscosity

Fuel Efficiency Index Oxidation Resistance Volatility Shear Stability Acid Resistance

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