Stručni rad
The influence of viscosity index improver type on shear stability of lubricating engine oils
Marija Milosavljević
; Rafinerija ulja Modriča, BiH
Omer Kovač
; Rafinerija ulja Modriča, BiH
Ilinka Mišić
; Rafinerija ulja Modriča, BiH
Pero Dugić
; Rafinerija ulja Modriča, BiH
Sažetak
During use of engine oils many reasons cause change in viscosity. Decrease in viscosity can be caused by shear stress or dilution of oil with fuel. Oxidation products and presence of soot lead to viscosity increase. In this paper, shear stability of different viscosity index improvers is tested using test method DIN 51382 and testing procedure FIAT 128A-064 in motor laboratory, where liquified petroleum gas was used as a fuel. Use of gaseous fuel excludes the possibility of oil dilution and soot generation. Lenght of test (25 hours) also excludes the possibility of oxidation product forming. Only change in viscosity comes as a consequence of shear stress. Based on the results, quality of used viscosity index improvers is evaluated and correlation is determined between the results of method DIN 51382 and the results of bench engine test. Olefin-copolymer improvers are less shear resistant comparing to hydrogenated star polyisoprene and hydrogenated styrene-butadiene copolymer improvers. It is also showed that DIN 51382 test method represents tougher shear stability test than the procedure FIAT 128A-064, which makes it especially suitable for assessment of improver quality.
Ključne riječi
lubricating engine oils; polymer viscosity index improvers; shear stability; test method DIN 51382; procedure FIAT 128A-064
Hrčak ID:
147321
URI
Datum izdavanja:
30.9.2015.
Posjeta: 1.328 *