ASTM D4742 Test Method for Oxidation Stability of Gasoline Automotive Engine Oils
ASTM D4742 Standard Test Method for Oxidation Stability of Gasoline Automotive Engine Oils by Thin-Film Oxygen Uptake (TFOUT)
11. Report
11.1 Report the oxidation induction time in min. Determine the induction time as the time period from the beginning of the test (Point A, Fig. 1) to the break point (Point B, Fig. 1).
12. Precision and Bias
12.1 The precision of this test method, as determined by statistical examination of interlaboratory results on break point time, is as follows:
12.1.1 Repeatability - The difference between successive results, obtained by the same operator with the same apparatus under constant operating conditions on identical test material, would in the long run, in the normal and correct operation of the test method, exceed the following values only in one case in twenty:
0.10 (x + 5 min)
where x is the mean replicate runs in min.
12.1.2 Reproducibility - The difference between two single and independent results obtained by different operators working in different laboratories on identical test material would, in the long run, in the normal and correct operation of the test method, exceed the following values only in one case in twenty:
0.22 (x + 5 min)
where x is the mean of results obtained, in min, by two different laboratories.
12.2 Bias - A bias statement is being developed.
12.3 The precision statements in 12.1.2 and 12.1.3 were determined from an interlaboratory study using the same batch of soluble metal mixture (Standard Reference Material SRM 1817 of the NIST).
NOTE 23 - The supporting test data from five cooperating laboratories are shown in Appendix X1. A research report (file No. RR: D02.1202) including the raw data and the statistical treatment of data is available upon request from ASTM Headquarters.
13. Keywords
13.1 oxidation stability; oxygen uptake; sequence IIID engine simulation; TFOUT
