| Abstract: | The wear protection performance of unique boundary chemistry (UBC), both while in the engine and after removal, was tested with reference to commercial API SG, API SH/ILSAC GF-1, and API SJ/ILSAC GF-2 quality oils in two 80,450 km field tests, in modified and standard sequence tests, and in radiotracer engine studies. The radiotracer tests of UBC added to an API SJ/ILSAC GF-2 quality oil replicated previously published results of wear reductions achieved in a comparison of an API SH/ILSAC GF-1 oil with and without UBC. In extended Sequence IIIE runs, two engines, each lubricated with the same API SH/ILSAC GF-1 oil, were unable to complete the tests as a result of excessive oil consumption due to hot stuck rings. In contrast, two Sequence IIIE engines lubricated with the same API SH/ILSAC GF-1 oil treated with UBC completed the extended test without incident, even though the UBC-treated API SH/ILSAC GF-1 oil replaced the API SH/ILSAC GF-1 oil for the first oil drain interval only. A fully formulated SAE 5W–30 oil, which contained a full complement of UBC (20%), met all the requirements of API SH/ILSAC GF-1 quality and gave very low average and maximum cam and cam plus lifter wear on standard ASTM Sequence VE and IIIE tests. The same API SH/ILSAC GF-1 oil without UBC gave somewhat higher wear on both tests, but both oils met API SH/ILSAC GF-1 requirements. Wear metals analysis of a field test of 36 taxicabs, which compared an API SJ/ILSAC GF-2 quality oil to the same oil treated with UBC for the first drain interval, and also to a UBC-treated oil at every oil change, showed a reduction in the rate of used oil Fe accumulation for both methods of UBC treatment. This test also revealed a striking impact on Fe levels from Si found in used oil samples during an episode of Si contamination in local gasoline supplies. Finally, in a field test of 10 taxicabs, with parts measured before and after testing, wear reductions were observed in rings and bearings in UBC-treated cabs compared to those with API SG oil alone. |
