An abnormally high engine oil temperature may be caused by which of the following?

An abnormally high engine oil temperature can indeed be caused by a low oil level. When the oil level is insufficient, there is not enough oil to adequately lubricate the engine components. This lack of lubrication increases friction between moving parts, which can raise the overall temperature of the engine and the oil itself. Additionally, a low oil level can lead to oil starvation, where the oil pump struggles to maintain proper oil flow and pressure, compounding the heating issue.

In contrast, using a higher grade oil could have a positive effect on the engine’s performance and temperature regulation, depending on the engine's design and operating conditions. Overheating of the engine could be a symptom of various issues, but it may not directly cause high oil temperature unless associated with low oil levels or other cooling deficiencies. An inadequate cooling system does indeed contribute to engine overheating, but it is more related to the overall engine temperature rather than oil specifically.