A comparison of gasoline direct-injection and port-fuel-injection vehicles: Part II - lubricant oil performance and engine wear

摘要

Four 1998 Mitsubishi Carismas, two equipped with direct-injection (GDI) and two with port-fuel-injection engines (PFI) were tested in a designed experiment to determine the effect of mileage accumulation cycle, engine type, fuel and lubricant type on engine wear and engine oil performance parameters. Fuel types were represented by an unadditized base fuel meeting EEC year 2000 specifications and the same base fuel plus synthetic deposit control additive packages. Crankcase oils were represented by two types (1) a 5W-30 API SJ/ILSAC GF-2 type engine oil and (2) a 10W-40 API SH/CF ACEA A3/B3-96 engine oil. The program showed that specific selection of oil additive chemistry may reduce formation of intake valve deposits in GDI cars. In general, GDI engines produced more soot and more pentane insolubles and were found to be more prone to what appears to be soot-induced wear than PFI engines. Again, proper selection of oil additive chemistry provided sufficient engine durability protection in both types of engines.