ASTM D5293-20

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Designation: D5293 − 17a D5293 − 20
Standard Test Method for
Apparent Viscosity of Engine Oils and Base Stocks
Between –10 °C and –35 °C Using Cold-Cranking Simulator
This standard is issued under the fixed designation D5293; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope*
1.1 This test method covers the laboratory determination of apparent viscosity of engine oils and base stocks by cold cranking
simulator (CCS) at temperatures between –10 °C and –35 °C at shear stresses of approximately 50 000 Pa to 100 000 Pa and shear
5 4 –1
rates of approximately 10 to 10 s for viscosities of approximately 900 mPa·s to 25 000 mPa·s. The range of an instrument is
dependent on the instrument model and software version installed. Apparent Cranking Viscosity results by this method are related
to engine-cranking characteristics of engine oils.
1.2 A special procedure is provided for measurement of highly viscoelastic oils in manual instruments. See Appendix X2.
1.3 Procedures are provided for both manual and automated determination of the apparent viscosity of engine oils using the
cold-cranking simulator.
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.5 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, health, and environmental practices and determine the applicability of
regulatory limitations prior to use. Specific warning statements are given in Section 8.
1.6 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
D2162 Practice for Basic Calibration of Master Viscometers and Viscosity Oil Standards
D2602 Test Method for Apparent Viscosity of Engine Oils At Low Temperature Using the Cold-Cranking Simulator (Withdrawn
1993)
D4057 Practice for Manual Sampling of Petroleum and Petroleum Products
2.2 ISO Standard:
ISO 17025 General Requirements for the Competence of Testing and Calibration Laboratories
3. Terminology
3.1 Definitions:
3.1.1 Newtonian oil or fluid, oil, n—one that an oil or fluid that at a given temperature exhibits a constant viscosity at all shear
rates.rates or shear stresses.
3.1.2 non-Newtonian oil or fluid, oil, n—one that an oil or fluid that at a given temperature exhibits a viscosity that varies with
changing shear stress or shear rate.
This test method is under the jurisdiction of ASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcommittee
D02.07 on Flow Properties.
Current edition approved Oct. 1, 2017June 1, 2020. Published October 2017June 2020. Originally approved in 1991. Last previous edition approved in 2017 as
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D5293 – 17D5293 – 17a. . DOI: 10.1520/D5293-17A. 10.1520/D5293-20.
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volume information, refer to the standard’s Document Summary page on the ASTM website.
The last approved version of this historical standard is referenced on www.astm.org.
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
*A Summary of Changes section appears at the end of this standard
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D5293 − 20
3.1.3 viscosity, η, n—the property of a fluid that determines its internal ratio between the applied shear stress and rate of shear
which is sometimes called the coefficient of dynamic viscosity and is a measure of the resistance to flow under stress, expressed
by:of the liquid.
τ
η5 (1)
γ
where:
τ = the stress per unit area, and
γ = the rate of shear.
3.1.3.1 Discussion—
It is sometimes called the coefficient of dynamic viscosity. This coefficient is thus a measure of the resistance to flow of the liquid.
In the SI, the unit of viscosity is the pascal-second; for practical use, a submultiple (millipascal-second) is more convenient and
is customarily used. The millipascal second is 1 cP (centipoise).
3.2 Definitions of Terms Specific to This Standard:
3.2.1 apparent viscosity, n—the viscosity obtained by use of this test method.
3.2.1.1 Discussion—
Since many engine oils are non-Newtonian at low temperature, apparent viscosity can vary with shear rate.
3.2.2 calibration oils, n—oils with known viscosity and viscosity/temperature functionality that are used to define the
calibration relationship between viscosity and cold-cranking simulator rotor speed.
3.2.3 check oil, n—a batch of test oil used to monitor measurement performance.
3.2.4 test oil, n—any oil for which the apparent viscosity is to be determined by use of this test method.
3.2.5 viscoelastic oil, n—a non-Newtonian oil or fluid that climbs up the rotor shaft during rotation.
4. Summary of Test Method
4.1 An electric motor drives a rotor that is closely fitted inside a stator. The space between the rotor and stator is filled with oil.
Test temperature is measured near the stator inner wall and maintained by removing heat with a controlled process to maintain a
constant stator temperature during test. The speed of the rotor is calibrated as a function of viscosity. Test oil viscosity is
determined from this calibration and the measured rotor speed.
5. Significance and Use
5.1 The CCS apparent viscosity of automotive engine oils correlates with low temperature engine cranking. CCS apparent
viscosity is not suitable for predicting low temperature flow to the engine oil pump and oil distribution system. Engine cranking
data were measured by the Coordinating Research Council (CRC) L-49 test with reference oils that had viscosities between
600 mPa·s and 8400 mPa·s (cP) at –17.8 °C and between 2000 mPa·s and 20 000 mPa·s (cP) at –28.9 °C. The detailed relationship
between this engine cranking data and CCS apparent viscosities is in Appendixes X1 and X2 of the 1967 T edition of Test Method
6 5
D2602 and CRC Report 409. Because the CRC L-49 test is much less precise and standardized than the CCS procedures, CCS
apparent viscosity need not accurately predict the engine cranking behavior of an oil in a specific engine. However, the correlation
of CCS apparent viscosity with average CRC L-49 engine cranking results is satisfactory.
5.2 The correlation between CCS and apparent viscosity and engine cranking was confirmed at temperatures between –1 °C and
–40 °C by work on 17 commercial engine oils (SAE grades 5W, 10W, 15W, and 20W). Both synthetic and mineral oil based
products were evaluated. See ASTM STP 621.
CRC Report No. 409 “Evaluation of Laboratory Viscometers for Predicting Cranking Characteristics of Engine Oils at -0°F and -20°F,” April 1968 available from the
Coordinating Research Council, 5755 North Point Pkwy, Suite 265, Alpharetta, GA 30022.
Supporting data have been filed at ASTM International Headquarters and may be obtained by requesting Research Report RR:D02-1402. Contact ASTM Customer
Service at service@astm.org.
Stewart, R. M., “Engine Pumpability and Crankability Tests on Commercial “W” Grade Engine Oils Compared to Bench Test Results,” ASTM STP 621 ASTM 1967,
1968. 1969 Annual Book of ASTM Standards , Part 17 (Also published as SAE Paper 780369 in SAE Publication SP-429.).
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5.3 A correlation was established in a low temperature engine performance study between light duty engine startability and CCS
measured apparent viscosity. This study used ten 1990s engines at temperatures ranging from –5 °C down to –40 °C with six
commercial engine oils (SAE 0W, 5W, 10W, 15W, 20W, and 25W).
5.4 The measurement of the cranking viscosity of base stocks is typically done to determine their suitability for use in engine
oil formulations. A significant number of the calibration oils for this method are base stocks that could be used in engine oil
formulations.
6. Apparatus
6.1 Two types of apparatus are described for use in this test method: the manual cold-cranking simulator (see Appendix X1)
and the automated CCS (see 6.2 and 6.3).
6.2 Automated CCS, consisting consisting of a direct current (dc) electric motor that drives a rotor inside a stator; a rotor speed
sensor or tachometer that measures rotor speed; a dc ammeter and fine current-control adjust dial; a stator temperature control
system that maintains temperature within 0.05 °C of set point; and a heat removal system with a temperature control system, a
computer, computer interface, and test sample injection pump.
6.3 Automatic Automated CCS, as as described in 6.2 with the addition of an automated sample table allowing multiple test
samples to be run sequentially under computer control without operator attention.
6.4 Calibrated Thermistor, sensor sensor for insertion in a well near the inside surface of the stator to indicate the test
temperature.
6.4.1 There must be good thermal contact between the temperature sensor and the thermal well in the stator; clean this thermal
well periodically and replace the small drop of high-silver-containing heat transfer medium.
6.5 Heat Removal System:
6.5.1 For stators with coolant contact, a refrigerator for the liquid coolant is needed to maintain coolant temperature at least
10 °C below the test temperature. When the coolant temperature is below –30 °C a two-stage refrigeration system is likely needed.
The length of the tubing connections between the CCS and the refrigerator should be as short as possible (less than 1 m) and well
insulated.
6.5.1.1 Coolant, Dry Methanol—If contaminated with water from operating under high humidity conditions, replace it with dry
methanol to ensure consistent temperature control.
6.5.2 For thermoelectric cooled stators, the liquid cooling temperature of the water or other appropriate liquid used in the
refrigeration system (chiller) should be set to approximately 5 °C in order to maintain the sample test temperature. To prevent ice
formation that can block the coolant flow path, it is suggested that a solution be used which contains approximately 10 % glycol
or that which conforms to the manufacturer’s guidelines.
6.6 Ultrasonic Bath, Unheated—(optional)—with an operating frequency between 25 kHz to 60 kHz and a typical power output
of ≤100 W, of suitable dimensions to hold container(s) placed inside of bath, for use in effectively dissipating and removing air
or gas bubbles that can be entrained in viscous sample types prior to analysis. It is permissible to use ultrasonic baths with operating
frequencies and power outputs outside this range, however it is the responsibility of the laboratory to conduct a data comparison
study to confirm that results determined with and without the use of such ultrasonic baths does not materially impact results.
7. Reagents and Materials
7.1 Calibration Oils—Low-cloud point Newtonian oils shall be certified by a laboratory that has been shown to meet the
requirements of ISO 17025 by independent assessment. The calibration oils shall be traceable to master viscometer procedures
described in Test Method D2162. Table 1 shows the sets of possible test oils to be used for each test temperature. Approximate
viscosities at certain temperatures are listed in Appendix X5, whereas exact viscosities are supplied with each standard.
8. Hazards
8.1 Observe both toxicity and flammability warnings that apply to the use of methanol or glycol.
8.2 If methanol is leaking from the apparatus, repair the leak before continuing the test.
9. Sampling
9.1 To obtain valid results, use an appropriate means of bulk sampling (see Practice D4057) to obtain a representative sample
of test oil free from suspended solid material and water. When the sample in its container is received below the dew point
Supporting data have been filed at ASTM International Headquarters and may be obtained by requesting Research Report RR:D02-1442. Contact ASTM Customer
Service at service@astm.org.
The sole source of supply of the apparatus known to the committee at this time is Cannon Instrument Co., State College, PA 16804. Website: www.cannoninstrument.com.
If you are aware of alternative suppliers, please provide this information to ASTM International Headquarters. Your comments will receive careful consideration at a meeting
of the responsible technical committee, which you may attend.
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TABLE 1 Calibration Oil Sets by Test Temperature
Test Temp –35 °C –30 °C –25 °C –20 °C –15 °C –10 °C
CL080 A . . . . .
CL090 A . . . . .
CL100 A A . . . .
CL110 B A . . . .
CL120 B A A . . .
CL130 B B A . . .
CL140 B B A A . .
CL150 B B B A . .
CL160 B B B A . .
CL170 B B B B A .
CL190 B B B B A .
CL200 B B B B A A
CL220 C B B B B A
CL240 C B B B B A
CL250 C B B B B B
CL260 . B B B B B
CL280 . C B B B B
CL300 . C B B B B
CL320 . C C B B B
CL340 . . C B B B
CL380 . . C B B B
CL420 . . . C B B
CL480 . . . C B B
CL530 . . . C C B
CL600 . . . . C C
CL680 . . . . C C
Group A Include at least one Preferred (bold)
or one Alternate.
Nominal Values
–35 °C to –25 °C; 800 mPa·s to 1500 mPa·s
–20 °C to –10 °C; 800 mPa·s to 1400 mPa·s
Group B Include at least 3. The selection is to be uniformly distributed over the range.
Nominal Values
–35 °C to –20 °C; 1000 mPa·s to 15 000 mPa·s
–15 °C; 1000 mPa·s to 13 000 mPa·s
–10 °C; 1000 mPa·s to 9000 mPa·s
Group C Include at least one.
Nominal Values
–35 °C to –20 °C; > 13500 mPa·s
–15 °C; >11 500 mPa·s
–10 °C; > 9000 mPa·s
temperature of the room, allow the sample to warm to room temperature before opening its container. When the sample contains
suspended solid material, use centrifuge to remove particles greater than 5 μm in size and decant off the supernate. Filtering is not
recommended. DO NOT shake the sample of test oil. This leads to entrainment of air, and a false viscosity reading.
9.2 For some sample types, such as viscous lube oils that are prone to having entrained air or gas bubbles present in the sample,
the use of an ultrasonic bath (see 6.6) without the heater turned on (if so equipped), has been found effective in dissipating bubbles
typically within 5 min.
10. Calibration
10.1 On installation of a new instrument or when any part of the viscometric cell or drive component (motor, belt, and so forth)
is replaced, set the motor current as described below. Recheck the motor current (as described in 10.3) monthly until the change
in motor current in consecutive months is less than 0.005 A and every three months thereafter.
NOTE 1—See Appendix X4 for a flowchart for calibration.
10.2 Temperature Verification—Using the temperature verification plugs, verify that the instrument is accurately computing the
correct temperature. (Only available on newer model instruments.)
10.2.1 Unplug thermistor connector from the back panel and insert blue TVP.
10.2.2 Enter the TVP resistance for the plug inserted in the software screen Service>CCS Temperature Verification Service, and
record the difference between the two temperature windows.
10.2.3 Repeat with second plug.
10.2.4 The recorded differences should be less that 0.06 °C. If they are greater, contact instrument service.
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10.3 Motor Current—Use the Set Motor Current option in the software with CL250 (3500 mPa·s) calibration oil as the sample.
This option will cool then soak the sample at test temperature of –20.0 °C in the same manner as for a test sample. For a
recalibration proceed with 10.3.1. If rechecking motor current, proceed with 10.3.2.
10.3.1 To set the rotor speed, 20 s after the drive motor turns on, monitor the speed reading and adjust to
0.240 KRPM 6 0.001 KRPM (displayed as SPEED on the computer monitor) by slowly turning the CURRENT ADJUST DIAL.
This should be completed with in 50 s to 75 s after the motor begins to turn. If more time is taken, repeat 10.3.
10.3.2 When rechecking the motor current, note the speed after the motor is on for 55 s to 60 s. If the speed is less than
0.005 KRPM from 0.240 KRPM, note the speed and current before continuing with normal operation. Alternatively, you can
readjust speed to 0.240 KRPM and note new current setting. Recalibration is optional unless two consecutive adjustments in motor
speed have been made in one direction since last calibration. If recalibration is not necessary, proceed with Section 11. Otherwise,
proceed with 10.4.
10.3.3 When rechecking the motor current, and the rotor speed is found to differ from 0.240 KRPM by more than 0.005 KRPM,
then readjust rotor speed to 0.240 KRPM, and record the current setting. Continue the calibration with 10.4.
10.4 Calibration Procedure—At each test temperature, calibrate the instrument with the oils listed for that temperature in Table
1 using the selection criteria below and the measurement procedure described in Section 11.
NOTE 2—Users of CCS 4/5 instruments using DOS based software need to run the set of calibration oils as samples. Users should enter the speed and
viscosity data into VISDISK to calculate calibration constants. These new constants would then be entered manually into the calibration data file used
by the CCS software. Contact their instrument supplier for assistance.
10.4.1 Calibration Oil Matrix Requirements—For each test temperature calibrated, use Table 1 and select a minimum of: one
calibration oil from Group A, three from Group B, and one from Group C. The Group B oils are to be selected so that the
distribution is uniform across the group. A minimum of ten data sets consisting of temperature, speed, and known viscosity are
required for determining the calibration coefficients in 10.5. A calibration oil can be included twice to achieve the required ten data
sets, however doing so will reduce the robustness of the calibration. When including a calibration oil a second time, they should
be placed so they are not in adjacent measurement positions. For example –35 °C calibration could have CL090, CL120, CL150,
CL170, CL190, CL240 followed by another set CL090, CL120, CL150, CL170, CL190, CL240 samples.
10.5 Calibration Equation—The computer program regresses the calibration data over the viscosity range at each calibration
temperature to fit the following equation:
B
η5 1B 1B ·~r! (1)
1 2
~r!
where:
η = the apparent viscosity,
B , B , B = the coefficients of regression, and
0 1 2
r = the rotor speed in KRPM.
10.6 The calibration will meet the following to be valid:
10.6.1 The regression coefficient shown by the software will be 0.99 or greater.
10.6.2 No calibration data that deviates by more than 1.6 % from Certified Reference Viscosity will be included. It is preferable
that all deviations be less than 1 %.
10.6.3 For a test temperature, if more than three pairs of data are excluded because of excessive deviation, repeat the calibration.
When a full calibration sample set is used on a repeat calibration within the four operating day time span, all data may be included
in calculating the coefficients of regression. When choosing to only run the excluded calibration oils, two calibration oils from the
retained data set are to be included in this sample set.
10.6.4 At a test temperature, the calibration data should be collected within the shortest period of time which is possible. When
the period of time is greater than four operating days between starting and completing the calibration at a given temperature, the
operator must rerun one or two of the earliest calibration oils and include the data in the analysis. This is to ensure the instrument
is operating in the same domain that it was initially. When it is the practice of the user to routinely add calibration data to the active
calibration data set, the four day period does not apply.
10.6.5 A calibration dataset at a test temperature shall contain at least 10 data points distributed over the available viscosity
calibration range after discarding any outliers.
11. Procedure for Automated and Automatic Automated CCS Operation
11.1 Place a minimum of 55 mL of the sample to be tested into a 60 mL sample container.
NOTE 3—When using mini-sample adapter, the instructions in Appendix X3 replace those in 11.1 – 11.3.
NOTE 4—When using an automatic sample changer, ensure the sample containers are designed to fit the sample tray and that the injection tube does
not reach to the bottom of the container, as this will avoid drawing any sediment into the instrument.
11.2 Enter sample identification and test temperature(s) for the sample.
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11.3 For instruments with automatic sample changer, repeat 11.1 and 11.2 until all sample containers are on the tray and entered
into the test matrix on the computer.
NOTE 5—It is recommended that a check oil be run with each sample set.
11.4 Start the sample testing following the software instructions. During the sample testing the instrument will cool the sample
to near the test temperature and hold it at that temperature for 180 s. After the soak, the rotor will start turning and the rotor speed
will be recorded, but only the average speed between 55 s and 60 s will be used to calculate viscosity.
NOTE 6—The new sample will automatically displace the previous test sample in the viscometric cell without the use of solvent. The temperature
control and running of the CCS motor will be computer controlled. The rotor speed measurement and viscosity calculation for the test sample are
performed and displayed by the computer.
11.4.1 When using a check oil and it does not fall within reproducibility of the expected value, the results are considered
suspect. If this occurs on two consecutive measurements, then recheck rotor speed with CL 250 at –20 °C. If rotor speed is not
within 0.005 KRPM of 0.240 KRPM, then investigate and resolve the cause of the deviation. Recalibration may be necessary.
12. Report
12.1 Report the calculated viscosity and temperature as displayed on the computer monitor or test report.
13. Precision and Bias
10,11
13.1 Precision —The precision of this test method with CCS-4/5 (contact cooling instruments) using version 4.x or higher
software and with CCS-2050/2100 (thermoelectrically cooled instruments) using ViscPro CCS software module for 2100 series,
as determined by statistical examination
...