Engine Oil:
What Is That Stuff We Pour Down Our Crankcase... Who Determines
The Quality?

Engine oil is the lifeblood of your home on wheels. Every time we fire-up our rigs, we are filled with the anticipation of imminent discoveries hiding just down the road.

Oil is the stuff that allows our comfortable Class C Motorhomes to get us there and back. Yet we really never give it a thought... other than to think about having to change it when our owners manual tells us to. Maybe it's time to look at this petroleum product just a bit. Our modern engines are assembled with very tight tolerances that demand the very best lubrication possible.

There is also the question of what is the best drain interval (length of time between oil changes).

It all starts with the American Petroleum Institute's (API) stamp of approval. This organization is responsible for dictating the voluntary standards called the Engine Oil Licensing and Certification System (EOLCS) adhered to by all the engine oil marketers.

Any manufacturer of oil that meets the EOLCS specified requirements are authorized to use the API Engine Oil Quality Marks commonly referred to as the API Service Symbol "Donut" and the Certification Mark "Starburst".

The white API Donut is divided into three parts:

• The oil's performance level is indicated on the top half of the donut.
  
  
  • If you see the letter "S" immediately followed with one of three letters, this indicates that this oil is to be used in a gasoline engine.
    
    
    • The letter SM indicates that this oil is to be used in all gasoline engines made after 2004. This oil has enhanced oxidation resistance, deposit & wear protection, and better low temperature performance over the life of the oil.
      
      
    • The letter SL is for 2004 and older automotive gasoline engines.
      
      
    • The letter SJ is for 2001 and older automotive gasoline engines.
      
      
• If you are running a diesel engine, it is important to check your owner's manual to find the correct engine oil used in your specific Class C Motorhome. There are engine oil standards going back to 1995 that have been developed to comply with emission control laws.
  
  The following gives a brief overview of oils available for diesel engines. For a more complete description of oil requirements refer to http://www.apicj-4.org/2009_ENGINE_OIL_GUIDE.pdf
  
  Look for the Alpha/Numerical descriptions that begin with a "C" to determine which oil is right for your vehicle.
  
  
  • The Alpha/Numerical description CJ-4 was introduced in 2006 for high-speed, four-stroke diesel engines designed to meet 2007 model year on-highway exhaust emission standards.
    
    
  • The Alpha/Numerical description CI-4 was introduced in Introduced in 2002 for high-speed, four-stroke diesel engines designed to meet 2004 exhaust emission standards implemented in 2002.
    
    
  • The Alpha/Numerical description CH-4 was introduced in 1998 for high-speed, four-stroke diesel engines designed to meet 1998 exhaust emission standards.
    
    
  • The Alpha/Numerical description CF was Introduced in 1994 for off-road, indirect-injected diesel engines.
    
    
• The oil's viscosity is identified in the center round "donut hole"
  
  
  • Viscosity is a simple measurement indicating flow capabilities... this usually refers to as how thick or thin the oil is at specified temperatures. It is referred to as a viscosity grade. The lower the viscosity grade, the better it will flow at a low temperature.
    
    
  • A multi-grade oil will show two numbers... such as 10W-30 oil. The first low number indicates how well the oil will flow in cold weather. The better the flow, the more protection is offered through lubrication. This will also help determine how fast, or quick, the engine will crank in cold weather. Simply put... the lower the number, the better the oil's performance in cold weather.
    
    
  • The second number (30) indicates lubricating performance at operating temperatures. Without this multi-grade combination, your 5W oil would not give good support at warm operating temperatures.
    
    
    • Essentially, a good multi-grade oil will provide proper flow parameters in cold weather, but will still have proper viscose characteristics to lubricate at higher operating temperatures.
      
      
  • It is important for owners to consult their owner's manual for matching the oil viscosity with the expected ambient temperature in which your Class C Motorhome will be used.
    
    
• The oil's energy conserving properties are indicated on the bottom half of the donut.
  
  
  • Gasoline engines that are labeled "Energy Conserving" have... simply put, passed the test that measures how well the oil can conserve energy. These results can show an increase in conservation on a fleet level, but the individual vehicle may not show a fuel savings. In other words... the results on an individual automobile are statistically too small to measure.
    
    
  • Diesel engines with a CI-4 category may show a "CI-4 PLUS" identifier. This indicates an oil formulated to show a higher level of protection against soot-related viscosity change.
    
    

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