ASTM D5133 low temp, low shear rate, viscosity/temp dependence of lubricants
ASTM D5133 standard test method for Low Temperature, Low Shear Rate, Viscosity/Temperature Dependence of Lubricating Oils Using a Temperature-Scanning Technique
9. Preparation of the Apparatus
9.1 Pre-treatment heating of samples using either a water bath or an oven.

9.1.1 Water Baths - Using boiling distilled water and correcting for barometric pressure (if significant because of altitude of the laboratory), check the calibration of the partial-immersion, calibrated mercury thermometer used in the pretreatment water bath by appropriate methods.

9.1.1.1 Check the constant temperature of the pre-treatment water bath after ensuring that it is filled with distilled water to a level 20 mm above the oil level in the immersed stators. The temperature should be constant at 90 +/- 2°C.

9.1.2 Ovens - Check the calibration of the temperature sensing device by appropriate methods. The temperature should be constant at 90 +/- 2°C.

9.1.2.1 Determine the length of time required to bring the sample up to 90°C. Use this time interval to establish the length of time the sample is held in the oven before being poured into the stator.

9.2 Preparing Liquid Cold-Bath - Check the liquid level in the programmable liquid cold bath. Fill bath to proper depth according to supplier's instructions at -5°C.

NOTE 2 - To ensure adequate cooling fluid height above the sample, it is advisable to fill the bath at -5°C to the appropriate level indicated by the manufacturer and to always bring the bath back to this temperature when on stand-by. This slows the evaporation rate. In addition, for many refrigerating baths, operation at some temperature moderately below room temperature maintains best operational response. Coolant should be added to the bath only at room temperatures to establish the correct fluid height as well as to avoid disruption of the cooling cycle at lower temperatures.

9.2.1 Install or check the cooling programs for the programmable liquid cold bath. The programs to be implemented are shown in Tables 1 and 2.

9.3 Check to see that the upper hook threaded (left hand thread) to the viscometer drive module's driveshaft is firmly finger-tightened. In the tightening process gently and slightly lift the driveshaft.

NOTE 3 - Do not pull down or push or pull laterally on the driveshaft as this may harm the internal jeweled bearing and perhaps bend the driveshaft as well.

10. Preparation for Calibration of the Test Cell
10.1 At room temperature pour the calibration oil, to the fill line (Fig. 1) of the stators to be calibrated and place in a suitable rack until ready.

NOTE 4 - Since the calibration oil is Newtonian in behavior throughout the low temperature test range and thus is non-gelling, no special pre-heating preparation is necessary.

10.2 Computer Data Acquisition and Analysis.
10.2.1 For setting up a computer automated analysis, refer to the owner's manual.

10.3 Turn the programmable liquid cooling bath on to control at -5°C.

11. Calibration of the Test Cell
11.1 Computer Method:
11.1.1 Set up cell and viscometer head as directed by the manufacturer using a reference Newtonian oil having an appropriate viscosity range and established as a standard for the test method.

11.1.2 Select special calibration cooling program shown in Table 1 on programmable liquid cooling bath according to bath manufacturer's instructions but do not start the program.

11.1.3 Open and enter required viscosity and temperature data in computer program.

11.1.4 From 3.4, now open main flow control valve for dry gas flow above liquid in stator at approximate rate of 10 mL/min per cell.

11.1.5 Simultaneously initiate:
11.1.5.1 Cooling program on cold-bath and

11.1.5.2 Data recording on computer according to bath manufacturer's instructions.

11.1.6 Collect and analyze complete recorded data using program developer's instructions.

11.1.7 The slope value of the best line through the collected viscosity/percent maximum torque data should be greater than 450 and the correlation coefficient, R, should be R not less than 0.999. If not, another calibration run should be made to check the results and if no improvement is shown, the program developer or equipment manufacturer should be contacted for advice.

12. Preparation for Analysis of the Test Oil
12.1 Pour the test oil into the stator to the fill line on the stator (see Fig. 1) in preparation for pre-heating and cover with a suitable material (such as an unpowdered latex finger cot) to prevent any loss of more volatile components or condensation of moisture.

NOTE 5 - A beaker may be used to pre-heat the test oil in an oven or in a water bath (if covered to prevent volatilization of components or condensation of moisture). In this case, pre-heated oils are to be poured into their respective stators within a few minutes after completing the pre-heating step.

12.1.1 Enter the identity of the test oils and test cells into the computer program according to the program instructions.

12.1.2 If using an oven for pre-heating, place samples in oven.

NOTE 6 - A rack to hold the sample-containing stators is convenient for either ovens or water-baths.

12.1.3 If using a water bath for pre-heating, place the samples in the heating bath.

12.2 After the samples have reached 90 +/- 2°C, using the time determined in 9.1.2.1, hold at this temperature for 1.5 to 2.0 h.

12.2.1 After pre-heating, remove the samples from the oven or water bath, exercising care in handling the hot rack (if used) and samples. Remove covers over the samples at this time. Proceed to 13.4 as soon as the glass stators have cooled sufficiently for handling.

NOTE 7 - Heating the rotor with the stator and test oil prolongs cooling considerably and is not acceptable for this protocol.