10. Group G (rail) oil and Z group (steam cylinder) oil 1. China has formulated the classification of G group (rail) oil (GB/T7631.-93) and machine tool lubricant selection standard (GB7632) —87) Group G oil is only one type, the name of the variety is only one letter “G†or the full name is L-G68, and the number is ISO viscosity grade. China has produced precision machine tool guide oil in the 1960s, and now has developed the guide rail oil standard (SH0361-92), replacing the original machine tool guide oil. This product is available in four viscosity grades of 32, 68, 100 and 150.