Studies on Solvent Refined Base Stocks

We are not yet at the stage (and likely we will never quite get there) when any of these or newer laboratory methods are regarded as the final acceptance criteria of a new lubricant. However, those mentioned above and many others have become essential as screening tests to identify the most probable candidates for final acceptance by industry-recognized methods (e.g., engine tests in the case of automotive or diesel engine oils). Ultimately, commercial experience proves success or failure of all laboratory tests. 

Inspection Results on a Pennsylvania Distillate Lubricant Stock and Selected Raffinate Fractions 

Oxidation studies were conducted between 140°C and 180°C for a 50 hour period with pure oxygen being circulated at 1 atm pressure with a flow rate of 15 L/hr through a 250 g sample. Volatile oxidation products were removed as formed by the gas flow and trapped downstream. At the end of the experiment the base stock was analyzed for acid content, amount of precipitates, and changes in viscosity. Oxygen consumption was measured throughout the 50 hour time period. 

FIGURE 5.1 Oxygen consumption curve types for base stocks at 140°C. 

Source M. R. Fenske, C. E. Stevenson, N. D. Lawson, G. Herbolsheimer, and E. F. Koch, Oxidation of Lubricating Oils—Factors Controlling Oxidation Stability, Industrial and Engineering Chemistry 

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