1.1 This practice covers three immersion oils to be used as replacements for ASTM No. 1, No. 2, and No. 3 immersion oils as called for in Test Method D471. The immersion oils will be designated as IRM 901 as a replacement for ASTM No. 1 oil, IRM 902 as a replacement for ASTM No. 2 oil, and IRM 903 as a replacement for ASTM No. 3 oil. The new reference oils have been developed under a new Committee D11 policy on reference materials (see Practice D4678 for background on the new policy and procedures). 1.2 The oils, IRM 901, IRM 902, and IRM 903, are similar but not fully equivalent to ASTM No.1, ASTM No. 2, and ASTM No. 3 oil, respectively. Refer to Table 1 for a description of the typical properties and specifications for these oils. 1.3 ASTM No. 5 Oil was accepted into Specification D5900 as an industry reference material in 2010 and designated as IRM 905. The composition, and properties of this immersion oil were not changed and the data in Table 1 remains current. It was listed among the IRM immersion oils in Test Method D471 in 2010. 1.4 This practice gives the necessary background and details on the changeover from the previous oils to the new oils. See Annex A1 for additional information on the commercial oils selected to replace AST