A CEC Investigation Group has examined temperatures in European gasoline engines. A survey showed top quartile average temperatures of 275°C (top ring groove), 147°C (sump) and 163° (cam/follower oil gallery and main bearing exit), under high speed driving conditions. Forecasts indicated sump temperatures would increase by 10-15°C, partly related to emissions control systems. Consequent problems were predicted as wear, scuffing, oil oxidation, ring sticking, high oil consumption, and bearing/seal distress. Development targets for lubricant high temperature performance tests are discussed, and the severities of a number of possible ring stick tests are compared.A similar CEC Survey concerned high-speed diesel engines. This covered both small passenger car, light van diesels, and larger truck diesels. Increasing ring and oil sump temperatures were identified. High temperature oil performance test needs for the smaller car diesel engine are discussed in the light of problems identified in the survey.