Turbocharging of gasoline-powered passenger car engines, to provide improved performance while maintaining good overall fuel economy, has been adopted by some U.S. and overseas builders. The high temperatures encountered in turbochargers can seriously affect the engine oil life. Under certain severe operating conditions excessive oil degradation deposits can be formed in the turbochargers which can lead to bearing failure. A vehicle chassis-rolls test procedure was developed to evaluate lubricant composition effects on turbocharger deposits and bearing condition. Evaluations of a number of different engine oils have demonstrated superior performance for one class of synthetic oil over high-quality mineral oils in lubricating the high-temperature areas of passenger car turbochargers.