• Drivers of high-performance cars often use Shell Rotella synthetic oil.sand car engine image by Clarence Alford from Fotolia.com
  
  Rotella is an engine lubrication oil produced by Shell. The Rotella family includes coolants, gear oils, tractor fluids and engine oils. The four basic groups of Rotella oils maximize engine performance, reduce wear and deposits and decrease emissions. Rotella offers suitable grades for diesel engines, high-performance cars and motorcycles. Shell produces multi-grade synthetic Rotella T Triple Protection oil and Rotella T6 --- a fully synthetic heavy-duty diesel engine oil.
  
  

Viscosity

• Weather conditions affect oil viscosity.snow image by Aleksandr Himcenko from Fotolia.com
  
  Viscosity measures an oil's the "flowability," meaning how readily it circulates through engine parts. An oil with too low a viscosity can shear and lose strength at high temperatures. Lower-viscosity oil may not pump to all engine parts. Manufacturers add polymers to light, base oils such as 5W to prevent them from thinning too much when they heat up. Rotella T6 has SAE viscosity grade of 5W-40 with kinematic viscosity of 87 at 40 degrees Celsius and a dynamic viscosity of 8,000 at -30 degrees Celsius. It provides protection under cold conditions but remains thick enough to protect at high temperatures.
  
  

Viscosity Index

• Oil viscosity also plays an important role in hot conditions.desert 8 image by Dusan Radivojevic from Fotolia.com
  
  This number, assigned to oils by the Society of Automotive Engineers (SAE), represents the oil's real viscosity at certain temperatures. Oils that meet specifications for winter use have a "W" included in their viscosity index, such as 10W, which has undergone testing at -20 degrees Celsius. Rotella T Triple Protection oils have SAE indexes of 135 for 15W-40 CJ-4 and 10W-30 CJ-4, indicating their ability to provide enhanced engine lubrication.
  
  

Flash Point

• Flash point varies between different oils.flame image by Marek Kosmal from Fotolia.com
  
  Flash point is the temperature at which oil gives off vapors that can ignite if exposed to a flame. The lower the vapor point, the greater the oil's tendency to burn off in hot cylinders; therefore, a high flash point is desirable. Rotella T6 has a flashpoint of 224 degrees Fahrenheit, and Triple Protection oils have a flash point of 204 degrees Fahrenheit.
  
  

Pour Point

• Outdoor temperatures also have an effect on oil pour point.motor image by Petr Efremov from Fotolia.com
  
  Pour point represents 5 degrees Fahrenheit above the point at which chilled oil shows no movement at the surface for five seconds when it undergoes an incline. This number represents the temperature at which oil will pump and maintain adequate pressure --- especially important in winter. The lower the pour point, the better. Rotella T6 has a pour point of -45 degrees Fahrenheit. Triple Protection oils have a pour point of -30 degrees Fahrenheit.
  
  

Percent of Sulfated Ash

• Oil burning in the engine creates ash.car engine image by itsallgood from Fotolia.com
  
  Ash is the solid material left over when oil reacts with sulfuric acid and burns. This number quantifies the amount of metallic anti-wear and detergent additives in oil. Zinc dithiophosphate is a detergent added to decrease wear. Rotella T6 and Triple Protection Synthetic oils both contain 1 percent sulfated ash.
  
  

Percent of Zinc

• Oil plays an essential role in smooth engine operation.engine image by goce risteski from Fotolia.com
  
  This number represents the amount of zinc used as an anti-wear, extreme pressure additive. It only applies during actual metal-to-metal contact in the engine --- a rare occurrence of the oil works properly. However, zinc compounds do prevent wear and scuffing. A level of .11 percent gives adequate protection with normal use. High-resolution, air-cooled motorcycles or turbocharged cars might need an oil with a higher zinc content.