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 D 471. 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 D 4678