ASTM D6984 Standard Test Method for Evaluation of Automotive Engine Oils in the Sequence IIIF, Spark-Ignition Engine
10. Calibration
10.1 Laboratory and Engine Test Stand Calibration - To maintain testing laboratory and engine test stand calibration status for Sequence IIIF engine oil testing, follow the procedures given in 12.13 and Annex A1 - Annex A4.

NOTE 11 - Paragraph 12.13 and Annex A1 - Annex A4 describe the involvement of the TMC in respect to calibration procedures and acceptance criteria for a testing laboratory and a test stand, and the issuance of Information Letters and memoranda affecting the test method.

10.2 Testing of Reference Oils - Periodically conduct tests on reference oils according to the following:
10.2.1 Conduct reference oil tests on each calibrated test stand within a laboratory according to TMC guidelines.

10.2.2 Obtain reference oils directly from the TMC. These oils are formulated or selected to represent specific chemical types or performance levels, or both. They are usually supplied directly to a testing laboratory under code numbers to ensure that the laboratory is not influenced by prior knowledge of acceptable results in assessing the test results. The TMC will determine which specific reference oil the laboratory shall test.

10.2.3 Assign a stand test number to each Sequence IIIF test. The number shall include the stand number, the number of Sequence IIIF tests conducted on the stand since the last reference oil test was conducted (0 to 15), and a sequential laboratory test number based on the starting date of the test. For example, 60-03-785 defines a Sequence IIIF test on stand number 60, which is the third non-reference oil test run on stand 60 since successful completion of a reference oil test, and was the 785th Sequence IIIF test in the laboratory. The only exception to this format is that the sequential laboratory test number shall have the letter A appended for the first rerun, B for the second, and so forth, for invalid or unacceptable reference oil tests.

10.3 Reference Oil Test Frequency - Conduct reference oil tests according to the following frequency requirements:
10.3.1 For a given, calibrated test stand, conduct an acceptable reference oil test after no more than 15 test starts have been conducted, or after 120 days have elapsed, whichever occurs first.

10.3.2 After starting a laboratory reference oil test, non-reference oil tests may be started on any other calibrated test stand.

10.3.3 Reference oil test frequency may be adjusted due to the following reasons: Procedural Deviations - On occasions when a laboratory becomes aware of a significant deviation from the test method, such as might arise during an in-house review or a TMC inspection, the laboratory and the TMC shall agree on an appropriate course of action to remedy the deviation. This action may include the shortening of existing reference oil calibration periods. Parts and Fuel Shortages - Under special circumstances, such as industry-wide parts or fuel shortages, the surveillance panel may direct the TMC to extend the time intervals between reference oil tests. These extensions shall not exceed one regular calibration period. Reference Oil Test Data Flow - To ensure continuous severity and precision monitoring, calibration tests are conducted periodically throughout the year. There may be occasions when laboratories conduct a large portion of calibration tests in a short period of time. This could result in an unacceptably large time frame when very few calibration tests are conducted. The TMC can shorten or extend calibration periods as needed to provide a consistent flow of reference oil test data. Adjustments to calibration periods are made such that laboratories incur no net loss (or gain) in calibration status. Special Use of the Reference Oil Calibration System - The surveillance panel has the option to use the reference oil system to evaluate changes that have potential impact on test severity and precision. This option is only taken when a program of donated tests is not feasible. The surveillance panel and the TMC shall develop a detailed plan for the test program. This plan requires all reference oil tests in the program to be completed as close to the same time as possible, so that no laboratory/stand calibration is left in an excessively long pending status. In order to maintain the integrity of the reference oil monitoring system, each reference oil test is conducted so as to be interpretable for stand calibration. To facilitate the required test scheduling, the surveillance panel may direct the TMC to lengthen and shorten reference oil calibration periods within laboratories such that the laboratories incur no net loss (or gain) in calibration status.

10.3.4 Donated Reference Oil Test Programs - The Surveillance Panel is charged with maintaining effective reference oil test severity and precision monitoring. During times of new parts, introductions, new or re-blended reference oil additions, and procedural revisions, it may be necessary to evaluate the possible effects on severity and precision levels. The surveillance panel may choose to conduct a program of donated reference oil tests in those laboratories participating in the monitoring system, in order to quantify the effect of a particular change on severity and precision. Typically, the surveillance panel requests its panel members to volunteer enough reference oil test results to create a robust data set. Broad laboratory participation is needed to provide a representative sampling of the industry. To ensure the quality of the data obtained, donated tests are conducted on calibrated test stands. The surveillance panel shall arrange an appropriate number of donated tests and ensure completion of the test program in a timely manner.

10.4 Evaluation of Reference Oil Test Results - The TMC evaluates the reference-oil test results for both operational validity and statistical acceptability. The TMC may consult with the Test Procedure Developer and test laboratory in case of difficulty, as follows:
10.4.1 Immediately upon receipt of the reference-oil test results from the test laboratory, the TMC evaluates the laboratories' decision on operational validity. For operationally valid tests, the TMC then evaluates the pass/fail parameters according to the Sequence IIIF Lubricant Test Monitoring System (TMC Memorandum 94-200). If the test is judged acceptable, the reference oil code will be disclosed by the TMC to the test laboratory. The TMC conveys to the test laboratory its preliminary findings based on the limited information available to them.

10.4.2 Subsequently, upon receipt of the information detailed in 11.4.4, the TMC reviews all reference-oil test results and reports to determine final test acceptability.

10.4.3 In the event the reference oil test is unacceptable, the test laboratory shall provide an explanation of the problem relating to the failure. If the problem is not obvious, all test-related equipment shall be re-checked. Following this re-check, the TMC assigns another reference oil for testing by the laboratory.

10.4.4 The TMC decides, with consultation as needed with industry experts (testing laboratories, Test Procedure Developer, members of the ASTM Technical Guidance Committee and of the Surveillance Panel, and so forth), whether the reason for any failure of a reference oil test is a false alarm, testing stand, testing laboratory, or industry-related problem. The Sequence IIIF Surveillance Panel shall adjudicate all industry problems.

10.5 Status of Non-Reference Oil Tests Relative to Reference Oil Tests - Non-reference oil tests may proceed within a given laboratory during reference oil testing based upon the following:
10.5.1 During the time of conducting a reference oil test on one test stand, non-reference oil tests may be conducted on other previously calibrated stands. If the reference oil test is acceptable to the TMC, consider that the non-reference oil tests have been run in a satisfactorily calibrated laboratory.

10.5.2 If a reference oil test is unacceptable, and it is determined that the problem is isolated to an individual test stand, consider that other test stands remain calibrated, and testing of non-reference oils may proceed on those other stands.

10.5.3 If a reference oil test is unacceptable, and it is determined that the problem is laboratory related, consider non-reference tests running during the problem period invalid unless there is specific evidence to the contrary for each test.

10.6 Status of Test Stands Used for Non-Standard Tests - If a non-standard test is conducted on a previously calibrated test stand, conduct a reference oil test on that stand to demonstrate that it continues to be calibrated, prior to running standard tests.

10.7 Data Acquisition and Control - The Sequence IIIF test requires the use of computerized data acquisition and control for all measured and controlled parameters outlined in this procedure. The system chosen by individual testing laboratories shall be capable of integrating with the Sequence IIIF process controller for many of these operations. The system shall also be capable of meeting or exceeding certain test specific performance requirements for maximum allowable response times and minimum allowable sample rates. In addition to the aforementioned requirements, the system shall also be capable of data logging to test specific archival files for each test parameter at minimum allowable record intervals; that is, no greater than two-minute intervals between successive logs for each parameter. See the Data Acquisition and Control Automation II Task Force Report (DACA II) and additional requirements as outlined in this procedure.
10.7.1 Sample Rate - The preferred sample rate is 100 Hz with the minimum allowable sample rate for the Sequence IIIF data acquisition and control system set at 1 Hz.

10.7.2 Measurement Accuracy - All measurement devices used for sensing speed, mass, flow, pressure, and temperature shall meet the minimum requirements as outlined in the DACA II report and also conform to total system response requirements as outlined by the TMC. The following is a list of minimum requirements for Sequence IIIF testing:

10.7.3 Temperature - Use only Specification E608/E608M, iron-constantan (Type J) thermocouples with an accuracy of +/- 0.5 °C over a range of 0 °C to 200 °C.

10.7.4 Pressure - For pressures >6.9 kPa, use only measuring devices with an accuracy of +/- 0.2 % of full scale for capacitive systems and +/- 0.25 % of full scale for strain-type systems. For pressures <6.9 kPa, use only devices with an accuracy of +/- 15 Pa for capacitive systems and +/- 14 Pa for strain-type systems.

10.7.5 Flow - For systems incorporating vortex shedding measuring (liquid) use +/- 0.75 % of reading; for vortex shedding measuring (gas) use +/- 3.0 % of full scale; for magnetic measurements use +/- 1.0 % of reading; for Coriolis measurements use +/- 0.75 % of reading.

10.7.6 Speed - For speeds measured by frequency, use +/- 1 r/min.

10.7.7 Mass - For masses measured by strain gauge, use +/- 0.25 % of full scale.

10.7.8 Measurement Resolution - The minimum resolution for all parameters shall be at least one-fourth the required system accuracy for that parameter; that is, if a test procedure requires an accuracy of 1.0 units, then the minimum resolution for that parameter = 0.25 unit.

10.7.9 System Time Response - Total system time response is the time required for the complete data acquisition system including all filtering, transducer lines, and surge tanks to measure a step change input for a given parameter. System response times should be determined by measuring the time required to reach a certain percentage of an imposed step change. For first order systems, use the time to 63.2 % of the imposed step change; for moving average systems use the time to 45.4 % of the imposed step change. See the TMC System Time Response Measurement Guidelines for methods of imposing step changes for calibration of Sequence IIIF test stands. See Annex A11 for maximum allowable system time responses for the data acquisition system.

10.7.10 Quality Index - Use of the quality index method of measuring the control capability of the test stand is required for certain parameters. The following formula should be used and a minimum of 2400 data records are required for the final, end-of-test values:

QI = quality index,
Xi = recorded test measurement parameter,
U = upper specification limit for that parameter,
L = lower specification limit for that parameter, and
N = total number of data points taken as determined from test length and procedural specified sampling rate. The upper and lower values used for QI calculations for the required parameters are listed in Annex A11.

10.7.11 Calibrate the stand instrumentation used for data acquisition and control, on all controlled and non-controlled parameters (see Annex A10), prior to every reference-oil test sequence, with the following exception:

NOTE 12 - A stand can be IIIF calibrated in accordance with this test method and IIIG calibrated in accordance with Test Method D7320. A stand that was IIIF or IIIG calibrated within the previous year can be calibrated as both a IIIF and IIIG stand. If the stand was not IIIF or IIIG calibrated within the past year, follow the LTMS guidelines for new stand requirements to obtain IIIF or IIIG calibration. If a test stand is calibrated in both the IIIF and IIIG test methods, conduct stand instrumentation calibrations as defined in 10.7.11 every 15 test starts. Calibrate the intake air-humidity system every six months, at a minimum.