Search Results

The present trend in the formulation of automotive engine lubricants is towards low viscosity products as to minimise the power loss due to viscous drag. Consequently, the engines may be exposed to adhesive wear, and in particular to scuffing of the cylinder-piston assembly. A tightening bench test has been developed using a two-stroke engine which is able to assess the anti-scuffing protection of automotive engine lubricants. Several types of lubricants have been evaluated: mineral oils, polyglycols, esters, polybutenes, alkylates, white oils.

The growing interest and concern over the problem of the high temperature viscosity of engine oils and its effect on the engine performance, following the proposal for revision of the SAE J 300, pushed the CEC Engine Lubricant Technical Committee to establish an Investigation Group (IGL 9) to investigate the subject of Viscosity Measurements at High Temperature. The Low Temperature aspects are mainly covered by the CEC Investigation Group IGL 8 and the German National Organization DKA Study Group. The IGL 9 Group agreed to circulate a questionnaire which was gratified with high degree of attention; 31 companies answered confirming the importance of the investigation and the requirement of viscosity measurements more realistic and in line with to day's engine operating conditions. A first screening work carried out on some reference oils has demonstrated the possibility of correlation among different bench measuring techniques and an engine.

This paper is a follow-up to Part 1 of the review on European work in the field of engine oil viscosity relevant to the revision of SAE J 300 classification. The European activity covers both low and high temperature aspects and is coordinated within C.E.C., Investigation Groups IGL-8 and IGL-9 respectively. The IGL-8 activity is well under way and results have already been generated in three main areas: the replies of the European engine builders to the SAE Questionnaire on low temperature practices and experience have indicated that there is quite a scatter in the low temperature viscometric requirements of different engines similar to that shown in the U.S.A. the Borderline Pumping Temperatures determined with four ASTM pumpability reference oils on eight different European engines have shown a wide spectrum of engine sensitivity although the average results are similar to the data generated by ASTM. regarding metrication of SAE J 300, European opinion expressed through the C.E.C.

The performance of single grade and multigrade oils and synthetic oils, has been evaluated in terms of friction power loss using an engine running on the test bed according to a modified Morse procedure. The results obtained show a good correlation between the engine performance and the rheological properties of the lubricants. The very low friction power loss experienced when using lubricants containing polymer can be explained by introducing the concept of anisotropic effective viscosity. Based on the good correlation between the measured and calculated friction generated in main bearings, a method has been devised for evaluating the temporary viscosity losses of multigrade oils by measuring the engine friction power loss and bearing temperatures.

The viscosity change of multigrade motor oils in service has been evaluated in a fleet representative of the present European car population. The evaluation covered air- and water-cooled engines, with conventional and integral gearboxes, and displacements ranging from 500-1750 cc. The effect of car, service, average ambient temperature, and type of polymer on the viscosity change of a lubricant has been estimated. The multigrade test oils have also been run in injector and bench engine tests in order to compare field testing results with laboratory techniques being developed.