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The author points out the necessity of a reevaluation of the SAE J300 Engine Oil Viscosity Classification System and of the instruments and bench tests developed over the last 30 years to predict low-temperature engine oil performance. Greater ease in starting engines at low temperatures as a consequence of lower friction, electronic timing, and fuel injection has resulted in engines with potentially much higher Critical Starting Viscosities than those which formed the basis for the low-temperature portion of the SAE J300 Classification System. Presenting some of the pertinent low-temperature data available from a well-known engine oil database, the author discusses the consequences of this situation with regard to a number of questions related to the present application of pumpability and startability bench tests, their limitations, and the importance of finding ways to meet the technical challenges.

This paper concerns a bench test developed to simulate the effect of engine operating conditions on the oxidation and deposit-forming tendencies of engine oils. The so-called Thermo-oxidation Engine Oil Simulation Test (TEOST) is carried out under temperatures and other environmental conditions identified as being significant in the internal combustion engine. These parameters can be readily modified to reflect different aspects of deposit conditions and/or different forms of the mechanical design of reciprocating engines. The most important aspect of the TEOST is the separation of the oxidation process into the two aspects believed to be present in the engine, (1) the preparation of oxidation precursors in the so-called ‘Reactor’ representing the engine sump and other moderately heated areas of oil exposure, and (2) the ‘Depositor’ representing those areas of the engine where temperatures are such that the completion of the deposit-forming oxidation mechanism can be induced.

Building on a previously presented concept of the Viscosity Loss Trapezoid (VLT), in this paper the author shows how the information contained in the VLT can produce a ‘viscous’ insight into the molecular weight distribution of an oil-soluble polymer such as a Viscosity Index Improver in formulated lubricants.

The ability of engine oils to provide hydrodynamic lubrication under operating conditions is essential. Such lubrication occurs at very high shear rates -- often well in excess of the current SAE J300 specification of one million reciprocal seconds. This paper presents data obtained for shear rates beginning as low as two hundred thousand to above five million reciprocal seconds as well as the technique developed to obtain these shear rates.

Previous studies to improve upon the Noack volatility test have reported a new approach which does not require toxic Wood's Metal for heating yet agrees well with Noack test results. In addition, the new approach collects 99% of the volatilized oil for optional analysis. This can be important apropos to phosphorus levels which are of concern regarding automotive exhaust catalyst life. To more closely compare the new approach with the Noack test, reference oils used in a recent ASTM volatility round-robin study were analyzed and the new approach was found to produce close agreement with the Noack technique and generally greater repeatability.

Foaming of lubricating oil during operation of any automotive mechanism is undesirable. To control this problem, anti-foaming additives are often part of the formulated oil. However, during use, the oil contacts the gasketing material used to seal the mechanism and may extract pro-foamants in sufficient quantity to overwhelm the anti-foamant additive. Recognition of this problem has led to several different in-house tests of oil/gasket compatibility seemingly giving divergent information and technical direction concerning correction of foam-inducing factors of both the oil and gasket. It seemed appropriate to investigate and quantify the relative importance of several of the presumed influences on oil/gasket interaction. To do this, a relatively simple test simulating oil/gasket contact in the operating mechanism has been developed around an air foam-bath and applied in a series of Taguchi matrix studies to determine the influential factors.