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Technical Paper

A Practical Approach to Jet Engine Lubricant Evaluation

Using actual parts from a typical jet engine, a test rig was designed and constructed. Operating under typical jet engine conditions, the rig was capable of differentiating between oils on the basis of seal deposits and used oil data. The possibility also existed that differences in carbon seal wear rate could be determined. Final correlation of the results with field information will determine if the differences noted are significant.
Technical Paper

Assessment of Shear Stability Methods for European Engine Oils

The high temperature permanent and temporary viscosities of oils run in a diesel injector shear stability test were compared with similar data for two European laboratory engine tests. Low shear rate permanent viscosity losses for oils run in selected European cars were compared with laboratory data. Shear stability as commonly determined by the diesel injector test and low shear rate viscosity measurements does not permit adequate assessment of the shear stability of engine oils. The viscosities measured at high shear rates and high temperatures appear to provide a more useful dimension in the characterization of oils than do standard viscosity measurements. Temporary viscosity losses tend to be larger than permanent viscosity losses.
Technical Paper

Corrosive Ring Wear - Does it Exist with Modern Lubricants and Ring Metallurgy?

Piston ring wear studies using an automotive engine and a radioactive wear measurement technique are presented to show the effects of compression ring face metallurgy and general lubricant composition on corrosive wear control. These results are correlated with those obtained in a single-cylinder laboratory engine. Results show that lubricant com-position is not critical respecting corrosion when chromium plated and molybdenum-filled compression rings are used, but is critical when plain cast iron rings are used. Although wear for the molybdenum rings may be slightly higher than that for chromium rings, no service problems are anticipated.
Technical Paper

Tailoring Automatic Transmission Fluid Shift Quality in the Laboratory

The influence of lubricant formulation and service degradation on automatic transmission shift quality was studied in full scale transmission cycling tests. Fluid frictional degradation was found to follow a well defined pattern. This pattern is influenced by fluid formulation as well as transmission environment. Both fluid oxidation and selective additive degradation affect the rate of progression through this pattern.
Technical Paper

The Impact of Basic Nitrogen Compounds on the Oxidative and Thermal Stability of Base Oils in Automotive and Industrial Applications

Nitrogen compounds present in mineral base oils at low concentrations are known to accelerate oil oxidation and to reduce the useful lifetime of formulated lubricants. Both Partial Least Squares and Neural Network analyses were employed to establish correlations between base oil composition and performance in industry standard thermal stability and oxidation tests. These correlations show that the “basic nitrogen” (BN) content of a base oil is a very important compositional feature determining its ultimate performance in a formulated lubricant which may be especially important for API Group II and III base oils that are relatively free of other pro-oxidants and naturally occurring, sulfur-containing antioxidants. The effect of BN species was also studied using model nitrogen compounds and it was confirmed that the pro-oxidant effect appears only in “basic” nitrogen containing molecules involving pyridine and quinoline derivatives.