Evaluation of SAE 0W-20 GF-4 Prototype Formulation in Severe Taxi Fleet Service

This paper reviews the relative performance of prototype SAE 0W-20 and SAE 5W-20 ILSAC GF-4 [1, 2] mineral oils in severe taxi fleet service. Both oils contained the same additive technology, formulated to 0.05% mass Phosphorus. This level was targeted to gain field experience with oils formulated to meet proposed chemical limits for the ILSAC GF-4 specification [1, 2]. Though the limits in the final ILSAC GF-4 specification were increased to 0.08% mass Phosphorus, the 0.05% mass Phosphorus maximum is again proposed for the ILSAC GF-5 specification [3]. Used oil Chemical and Physical analysis was carried out at both interim and final drains (10,000 miles). Oil and fuel consumption were also monitored during the test. After a total mileage accumulation of 100,000 miles per vehicle, engine teardowns and physical ratings were performed on key engine components. It was concluded the performance of both lubricants was equivalent and acceptable. An exception to this was the fuel economy benefit of the SAE 0W-20 grade.