In Japan, turbocharged passenger cars have recently been introduced with increased improvements in fuel economy and engine performance. However, a turbocharger is driven by hot exhaust gas, so that an engine oil with superior thermal stability is required.
After studying a turbocharged engine's thermal effects, two laboratory screening tests that correlate with dynamometer engine tests were established. These tests, termed the panel coking test and the high temperature panel corrosion test, enable one to evaluate base oils, additive components and viscosity index improvers for a given engine oil.
Finally, a 10W-30 engine oil formulated by using these tests, showed superior deposit control and anticorrosion performance in the dynamometer engine test and actual driving conditions.