Engine Oils: Making the Best Choice
Start with the Owner's Manual
Every vehicle manufacturer has a recommendation on what type of oil to use. They also offer guidelines as to how often the oils should be changed. The interval between engine oil changes is also dependent on how frequently and how long a truck is driven, and the driver's driving style.
The Plot Thickens — or Does It?
The Society of Automotive Engineers (SAE) long ago developed a system for grading motor oils according to their viscosities, or "weight." SAE J300 standard measures an oil's viscosity and assigns grades depending on that viscosity. In order of ascending viscosity, the SAE grades are 0, 5, 10, 15, 20, 25, 30, 40, 50 and 60. The first four are designated with the letter 'W' to signify a winter, cold-start viscosity. A 20- or 25-grade oil may or may not come with a 'W', depending on whether it is being used to designate a cold-start viscosity or hot viscosity grade (no W).
A single-grade oil does not use a polymer additive (Viscosity Index Improver) to change its viscosity. There are eleven single-grade oils: 0W, 5W, 10W, 15W, 20W, 25W, 20, 30, 40, 50 and 60. A multi-grade oil usually (but not always) employs a Viscosity Index Improver additive to alter its viscosity. The designations for multi-grade oils are the ones familiar to many motorists (10W-30, for example) and include two numerical designations -- a cold-start number and a hot number for when the engine is at operating temperature. How an oil's viscosity changes with temperature is dependent on the additives a manufacturer uses.
Some fleet managers or operators select thicker oils, believing they offer better protection to engine components than thinner grades. However, as manufacturers produce engines and components to ever-tightening tolerances, a thicker oil may not be able to flow into the tighter clearances between parts, causing sluggish performance, decreasing engine efficiency, and increasing fuel consumption. Consequently, a thinner oil may seem counterintuitive but still be the best choice.
Contact us to see which engine oils have "OEM" approvals for equipment and engines.