LO 10-8 Describe the purpose of scheduled oil sampling and outline the steps to properly obtain an oil sample

LO 10-08: Describe the purpose of scheduled oil sampling and outline the steps to properly obtain an oil sample.

Oil Life Algorithm Systems

The engine ECU continuously monitors engine operating conditions to determine when to change oil. Software-based calculations use a formula or algorithm with input variables for engine operating conditions to determine oil life. Because oil degradation is associated with combustion events, analyzing combustion conditions can accurately determine when oil life has reached its maximum value. For example, when a cylinder fires, a small amount of oil is exposed to combustion and destroyed. Combustion gases containing acids, unburned fuel, water, and other byproducts leak past the piston rings and react with the engine oil. Diesels tend to generate much more soot and acidic combustion blowby in the crankcase. It is also known that oil temperature exerts a strong influence on the deterioration of oil quality Figure 59. As oil temperature increases, the rate of oxidation accelerates, which can lead to oil thickening. Turbochargers subject motor oils to high temperatures and are more prone to form engine deposits. Colder oil temperatures increase the concentration of oil contaminants, such as fuel and water. Depending on the vehicle and engine type, each engine receives its own unique algorithm to determine engine oil life.

FIGURE 10-59: Engine oil life is influenced by its operating temperature.

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