This SAE Standard defines the limits for a classification of engine lubricating oils in rheological terms only. Other oil characteristics are not considered or included.
This proposed revision would change the minimum high-temperature, high-shear rate viscosity for SAE 0W-40, 5W-40 and 10W-40 viscosity grades to 3.5 mPa's from the current limit of 2.9 mPa's. The rationale is that moving from an SAE xW-30 to an SAE xW-40 should provide increased bearing oil film thickness in an operating engine, which is not fully reflected in the current version of the Standard. This proposal was developed by a working group within the SAE Engine Oil Viscosity Classification Task Force, and the EOVC membership supported its move to formal ballot. The working group analysis of aftermarket databases covering North America, Europe and Asia-Pacific indicated a minimal impact on commercially available engine oils (<1% affected by the proposed change).