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Diesel lubrication oil contaminated with sunflower oil fuel was exposed to conditions simulating an engine crankcase environment to quantify and elucidate the mechanisms of loss of alkalinity and oil mixture thickening. Oxygen was found to be a dominant factor in both phenomena as was the presence of metallic copper catalyst. Triglyceride polymerization causing oil thickening does not appear causally related to alkalinity loss, but rather seems governed by a separate free radical mechanism.
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Rewolinski et al. (1985) studied this question.
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