THE IMPORTANCE OF ENGINE OIL
Oil is truly the life blood of your engine.  Most modern engines require synthetic oil, and each vehicle has its own factory recommendations for oil weight and brand.   Unlike the quick-lube shops and even some dealerships, we use only the factory recommended oil for your vehicle.  It is more expensive, but the old adage “you get what you pay for” is very true when it comes to oil.
Contaminants are deadly enemies of an engine. They enter with the air flow and are also generated by the friction of metal against metal. These facts may astound you: for every 100 gallons of gasoline burned in an engine, the following by-products are produced: 
  • 90 to 120 gallons of water 
  • 3 to 10 gallons of unburned gasoline 
  • 1/2 to 3 pounds of soot and carbon 
  • 1/4 to 1 pound of varnish 
  • 1 to 4 pounds of sulfuric and nitric acid 
A measurable percentage of these by-products end up in the motor oil. Detergents and dispersants in the oil are designed to keep most of these contaminants neutralized by suspending them in the oil as microscopic particles so they don't form sludge, damaging deposits and corrosion. When the waste materials are dispersed properly in the oil, the filter can trap the larger particles. During an oil change, the contaminants too small to be filtered are drained out with the engine oil.


HOW SLUDGE FORMS

BMW-Engine-Sludge
Engine sludge has the consistency of warm chocolate pudding. Imagine the engine of your car, with all its tiny passages, trying to pump that stuff around. Sludge formation begins when the chemically suspended particles of contaminants start to settle out of the oil. It's a fairly daunting task for engine oil to suspend all the contaminants thrown at it. Eventually even the best oil will reach it’s “breaking point" if it’s not changed frequently enough. This breaking point is either when there are too many contaminants to handle or when the oil's chemical defenses are weakened, and it is caused by two main things: excessive accumulation of contaminants in the oil and chemical changes in the makeup of the oil itself (depletion of the additives and oxidation). 
As more and more particles are suspended, less of the oil additives are available to do their job. Knowing this makes it easy to see why too much time between oil changes can cause the oil to reach its "breaking point".
 Even the best synthetic motor oil can only do its job effectively for 5,000 to 7,500 miles, depending on driving conditions. Running the engine low on oil for a prolonged period of time can also cause sludge. The detergent and oxidation inhibitors are important components of the additive package that prevent sludge from forming. When an engine is run low on oil, these additives have to work overtime to do their job. There is simply less of the additive package available to do the work of suspending particles and preventing oxidation (thickening) of the oil. Running an engine one quart low on oil for just 55 hours can increase the viscosity, or the thickness, of the oil by over 1000%!!! That’s like running 5,000W oil in their car's engine!