A lubricant composition comprising a polyalkylene glycol base oil component in an amount of at least 60 parts by weight based on 100 parts by weight of said lubricant composition, wherein said lubricant composition has a kinematic viscosity at 100°C of from 4 to 50 cSt and a kinematic viscosity at 40°C of from 20 to 700 cSt, each measured in accordance with ASTM D445, wherein said polyalkylene glycol base oil component comprises: a polyalkylene glycol A being a homopolymer formed from propylene oxide and having a kinematic viscosity at 100°C of from 2 to 15 cSt and a kinematic viscosity at 40°C of from 15 to 70 cSt, each measured in accordance with ASTM D445, and a polyalkylene glycol B being a homopolymer formed from propylene oxide and having a kinematic viscosity at 100°C of from 10 to 50 cSt and a kinematic viscosity at 40°C of from 60 to 250 cSt, each measured in accordance with ASTM D445, wherein said polyalkylene glycol B has a kinematic viscosity that is greater than the kinematic viscosity of said polyalkylene glycol A at 100°C and 40°C wherein said polyalkylene glycol base oil component is water-insoluble, wherein said polyalkylene glycol base oil component comprises: said polyalkylene glycol A in an amount of from 5 to 40 parts by weight based on 100 parts by weight of said polyalkylene glycol base oil component, and said polyalkylene glycol B in an amount of from 40 to 70 parts by weight based on 100 parts by weight of said polyalkylene glycol base oil component, the lubricant composition having a viscosity index of from 170 to 250 as measured in accordance with ASTM D2270 and further comprising a diester. a polyalkylene glycol A being a homopolymer formed from propylene oxide and having a kinematic viscosity at 100°C of from 2 to 15 cSt and a kinematic viscosity at 40°C of from 15 to 70 cSt, each measured in accordance with ASTM D445, and a polyalkylene glycol B being a homopolymer formed from propylene oxide and having a kinematic viscosity at 100°C of from 10 to 50 cSt and a kinematic viscosity at 40°C of from 60 to 250 cSt, each measured in accordance with ASTM D445, wherein said polyalkylene glycol B has a kinematic viscosity that is greater than the kinematic viscosity of said polyalkylene glycol A at 100°C and 40°C wherein said polyalkylene glycol base oil component is water-insoluble, wherein said polyalkylene glycol base oil component comprises: said polyalkylene glycol A in an amount of from 5 to 40 parts by weight based on 100 parts by weight of said polyalkylene glycol base oil component, and said polyalkylene glycol B in an amount of from 40 to 70 parts by weight based on 100 parts by weight of said polyalkylene glycol base oil component, the lubricant composition having a viscosity index of from 170 to 250 as measured in accordance with ASTM D2270 and further comprising a diester. said polyalkylene glycol A in an amount of from 5 to 40 parts by weight based on 100 parts by weight of said polyalkylene glycol base oil component, and said polyalkylene glycol B in an amount of from 40 to 70 parts by weight based on 100 parts by weight of said polyalkylene glycol base oil component, the lubricant composition having a viscosity index of from 170 to 250 as measured in accordance with ASTM D2270 and further comprising a diester. <EOS>