Flame retardant lubricating oil compositions

Abstract

Lubricating oil compositions having low flammability properties and good low temperatures suitable for use as hydraulic fluids comprise a major amount of GTL base oil, optionally a minor amount of polyolphaolefins, an additive amount of about 5 to 30 wt % of dicarboxylic acid ester and minor amount of a pour-point depressant.

1 . A flame retardant hydraulic fluid comprising a base oil consisting of GTL base oil and optionally up to 50 wt % PAO, from about 5 to about 30 wt % dicarboxylic acid based on the total weight of the fluid, from about 0.5 to about 5 wt % of a pour point depressant based on the total weight of the fluid, wherein the GTL base oil has a kinematic viscosity at 100° C. in the range of about 2 mm 2 /s to 10 mm 2 /s and a pour point of about −30° C. or higher, the hydraulic fluid having a pour point of −55° C. maximum. 
   
   
       2 . The flame retardant hydraulic fluid of  claim 1  wherein the base oil consists of GTL base oil and optionally up to 40 wt % PAO. 
   
   
       3 . The flame retardant hydraulic fluid of  claim 1  wherein the base oil consists entirely of GTL base oil. 
   
   
       4 . The flame retardant hydraulic fluid of  claim 1 ,  2  or  3  wherein the hydraulic fluid exhibits a flame propagation rate of about 2 mm 2 /s or less by ASTM D5307.