Identificação e quantificação do teor de umidade em óleo lubrificante automotivo: um estudo de caso

Abstract

Lubricating oil is essential for operating internal combustion engines, protecting parts, reducing friction, and dissipating heat. However, water can lead to corrosion, oxidation, and sludge formation, reducing viscosity, and lubricating capacity. This study reports moisture determination in an engine lubricating oil. The engine lubricating oil and the radiator water were changed at a gas station. The position is very close to the front of the truck. However, the engine melted after this change after 16 km of driving. Thus, a technical report was conducted and reported using six different analytical strategies determining moisture in lubricating oil: centrifugation and weighing in a balance, oven drying and weighing in a balance, drying and weighing in a thermogravimetric analyzer, drying and weighing in a moisture balance analyzer, simple distillation and weighing in a balance, and identification by infrared spectroscopy. The moisture content in the sample was 46.1 ± 7.7%, corroborating with water addition in the lubricating oil. The accuracy was assessed through recovery assessment (90 ± 5%) and results comparison. The importance of controlling humidity in commercial lubricating oils is also highlighted, and analytical strategies described in the present study can be alternatives to certify the quality of commercial lubricating oil.