Oxidation
Method: Unsubtracted JOAP (Joint Oil Analysis Program)
Units: None

Oxidation occurs when oxygen attacks petroleum fluids. The process is accelerated by heat, metal catalysts, and the presence of water, acids, or solid contaminants. As oil oxidizes, it loses its lubricating properties and forms resins. As viscosity increases, thickening of the oil and piston deposits are the most common effect of oxidation.

Oxidation is determined by measuring toluene insolubles expressed in absorbance units at a specific wavelength in the infrared scan.

While all contaminants should be considered detrimental to diesel engines, the chemical action of oxidation should be considered the most harmful. Oxidation can occur in natural gas engines, transmissions, and hydraulic systems, as well as diesel engines.

Effects of Oxidation: -

• Oil Filter plugging.
• Reduction of oil's lubricating properties.
• Can increase oil viscosity.
• Can lead to piston deposits.
• Can cause piston ring sticking.

Benefits of Determining Oxidation: -

• Correct management of oil change period when used in conjunction with wear metal analysis.
• Measures the oil's ability to control oxidation.
• Can be an indication of high temperature operation, oils exposure to air, and/or extended oil-change periods.

Probable Causes of Oxidation: -

• High temperature operation caused by defective or incorrect water temperature regulators or lugging (excessive load) conditions.
• Oil drain intervals extended beyond the oil's ability to control oxidation.
• Oils exposure to air.
• Unacceptable levels of copper, iron, or ethylene glycol.
• Abnormal combustion, gas blow-by.