Temporary Viscosity Loss of Engine Oils

A study on the temporary viscosity loss under high shear rates of engine lubricants was started in order to:

1. 1.
   Set up a new viscometer, more correlate with the engine than the present ones.
2. 2.
   Clarify the influence of this phenomenon on the lubricant performances.

Preliminary results on a pressoviscometer are discussed.

Namely it is underlined that the temporary viscosity loss affects both multigrade and unigrade oils, even if at different levels, and in different ways.