Why do I have to top off my engine oil?

When discussing the issue of oil consumption, we must keep in mind that there are only two ways oil is consumed in a diesel engine: Oil is either burned in the combustion chamber or it leaks through seals or gaskets.

There are also a number of factors or conditions that can affect the amount of oil an engine consumes.  Some of the factors that affect oil consumption include engine idle time, driving conditions, load, terrain, engine operating temperature, oil volatility, fuel dilution, and miles on the engine.  Another important point to remember is that no two engines are alike.

You may have noticed that engine oil consumption has been reduced in late model trucks.  New oils control piston deposits, which results in better oil consumption control. Newer piston and piston ring designs along with changes in engine operating conditions are also factors.

Oil formulation can help provide the best oil consumption control.  Premium motor oils are formulated to exceed the most current requirements of all North American truck engine manufacturers, as well as those of the American Petroleum Institute.  All Shell Rotella® engine oils are formulated with a careful balance of detergent, dispersant, antioxidant and anti-wear chemistry that qualifies them to be used in extended service.  Extensive field testing has further documented their exceptional performance.

Adding a gallon of oil every few thousand miles was once common. We now see late-model engines that can go an entire drain interval without requiring any additional oil. However, we still recommend you check your oil daily and top off as required.

To further help monitor your engine's condition, we recommend an oil analysis program.  It is one of the most effective ways to monitor your engine's condition. A regular oil analysis program helps you build a historical database and monitor trends across a variety of areas.  Ideally, you want to analyze a sample of used engine oil after every oil change.