ASTM D4683-09

Viscosity values at the shear rate and temperature of this test method have been indicated to be related to the viscosity providing hydrodynamic lubrication in automotive and heavy duty engines in severe service.

The viscosities of engine oils under such high temperatures and shear rates are also related to their effects on fuel efficiency and the importance of high shear rate, high temperature viscosity has been addressed in a number of publications and presentations.

1.1 This test method covers the laboratory determination of the viscosity of engine oils at 150 °C and 1.0·10⁶ s⁻¹ using a viscometer having a slightly tapered rotor and stator called the Tapered Bearing Simulator (TBS) Viscometer.

1.2 The Newtonian calibration oils used to establish this test method range from approximately 1.2 mPa·s to 7.7 mPa·s at 150 °C.

1.3 The non-Newtonian reference oil used to establish the shear rate of 1.0·10⁶ s⁻¹ for this test method has a viscosity closely held to 3.55 mPa·s at 150 °C.

1.4 Manual, semi-automated, and fully automated viscometers were used in developing the precision statement for this test method.

1.5 Application to petroleum products other than engine oils has not been determined in preparing the viscometric information for this test method.

1.6 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.6.1 This test method uses the milliPascal·second (mPa·s) as the unit of viscosity. This unit is equivalent to the centipoise (cP).

1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.