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2005 Police Fleet Expo Sessions: Lubricants
The session on selecting the “Right Lubricants” was presented by Chris May with ExxonMobil. Good motor oils should clean the engine of contaminants by reducing the build-up of sludge on engine parts and by keeping particles in suspension. They should also seal the piston and liner for optimum engine efficiency. Furthermore, good motor oils should resist high temperature degradation and provide low temperature lubrication (as low temperature flow affects engine durability), and prevent rust and corrosion of metal engine parts.
However, while the ability to perform these functions should be inherent to any good motor oil, the synthetic oils stand apart in terms of quality by meeting and sometimes exceeding these performance criteria. But to truly understand the advantages and disadvantages of selecting certain oils, it is important to first examine the standards and performance measures used to gauge their quality.
Automakers developed the specifications set forth by the International Lubricant Standardization and Approval Committee (ILSAC). However, it should be noted that quality levels change every three to four years due to recent technological innovations that require oil today to work harder than ever. Look for the special seal on the front of container labels: API Certified.
The API Service Symbol includes the API service designation and the Society of Automotive Engineers (SAE) viscosity grade. The service designation indicates the quality rating of the oil, with SM as the highest quality for gasoline engines. SAE viscosity grades differentiate between low temperature conditions (i.e., SAE 10W) and high temperature conditions (i.e., SAE 30). When selecting a viscosity grade, consider the OEM Recommendation/Owner’s Manual, operating temperature, vehicle operation, vehicle age, and severe operating conditions.
What makes some motor oils better than others? First, consider their basic composition. Motor oils consist of a base stock and performance enhancing additives. The overall performance of a motor oil is impacted significantly by the composition of its base stock, whether it be conventional mineral oil, hydroprocessed (highly refined) mineral oil, or chemically built synthetics.
Enhancing performance by working with the base stock, some common additives include detergents, antioxidants, and antiwear additives. Besides conventional oil and hydroprocessed oil, there are also synthetic blends which are comprised of a conventional mineral base stock and a synthetic. Fully synthetic motor oils, however, consist of a base stock by chemical synthesis or extreme refining and purification.
What gives synthetic oils an edge? Stop-and-go driving, high temperature, cold start-ups, fast accelerations, frequent idling, and other extreme driving conditions cause motor oils to perform differently. Conventional motor oils can break down in extreme hot temperatures, and even solidify under extreme cold conditions.
Synthetic blends (semi-synthetic oil) tend to vary based on their composition. They generally perform only a little better than conventional formulas. Fully-synthetic motor oils, however, protect against engine wear in all driving conditions and temperatures, consistently outperforming both conventional motor oil and synthetic blends. In short, fully-synthetic motor oils provide the best possible engine protection. In lab and field engines, synthetic motor oils outperform conventional lubrications, providing better wear, excellent cleanliness, and proven endurance.
Published in Police Fleet Manager, Sep/Oct 2005
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