Field tests have been run in a variety of vehicles to assess the wear and cleanliness performance of API SG (SG) compared to API SF (SF) and lower quality oils. The field tests were run in simulated delivery service with light trucks and in taxis. Oil drains and filter changes were maintained at 24,000 km to provide severe service conditions. Comparing overhead cam wear in the Sequence V-D, Sequence VE and the field demonstrated that SG quality oils have a significant margin of safety for field wear control. SG quality oils provided excellent engine cleanliness protection in the field that was significantly better than the cleanliness afforded by SF quality oils. Both SF and SG quality oils performed well in bearing wear protection. Used oil analyses were helpful for assessing the overall field performance of engine oils.