A Comparative Analysis of the Viscosity of Three Engine Lubricants for Gasoline Engines Post 10,000 Kilometer  Service Interval: -

Krissadang  Sookramoon; Chumpon  Patummakason; Benjapa  Kaithong

doi:10.53848/ssstj.v13i1.1180

Authors

Krissadang Sookramoon Valaya Alongkorn Rajabhat University
Chumpon Patummakason Valaya Alongkorn Rajabhat University
Benjapa Kaithong Valaya Alongkorn Rajabhat University

DOI:

https://doi.org/10.53848/ssstj.v13i1.1180

Keywords:

Engine oil, Viscosity, Mileage, Oil degradation, Saybolt Furol Universal Viscometer, ASTM D445

Abstract

Vehicle maintenance is essential for ensuring efficient operation and extending service life. Engine oil is a crucial component that lubricates various parts of the engine, such as the camshaft, crankshaft, connecting rods, and pistons. It helps reduce friction and dissipates heat generated from engine operation. However, over time, the properties of engine oil gradually change, particularly its viscosity, which may decrease and affect engine performance, potentially leading to mechanical problems. Therefore, studying the changes in engine oil viscosity after prolonged use is vital in determining the appropriate oil change intervals and guiding car owners in proper vehicle maintenance. This study aims to evaluate the changes in kinematic viscosity of three types of gasoline engine oils (SAE 10W-30, SAE 10W-40, and SAE 20W-40) after 10,000 km of operation, based on ASTM D445 standard, and to compare their properties with fresh oil conditions. The analysis showed a clear decrease in viscosity for oil samples used for 10,000 km (second dataset) compared to the fresh oil samples (first dataset), with flow time decreasing from 95 to 66.5 seconds, 105 to 75.6 seconds, and 115 to 82.8 seconds for SAE 10W-30, 10W-40, and 20W-40, respectively. Similarly, the kinematic viscosity dropped from 45.2 to 31.64 cSt, 50.0 to 36.0 cSt, and 55.1 to 39.67 cSt, respectively. A slight reduction in oil density after 10,000 km was also observed. However, the viscosity classifications according to SAE standards at 40°C remained consistent. These results indicate changes in the physical properties of engine oil after use, which may affect lubrication performance and engine protection.

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