All paraffinic, low temperature hydraulic oils

Abstract

A paraffinic hydraulic oil having a shear stability index of from 0 to 20, a shear loss of less than 7% as measured by ASTM D5621 and a Brookfield viscosity the same or better than a naphthenic oil of the same viscosity grade is provided. The hydraulic oil includes 5 wt % to 90 wt % of a first paraffinic oil having a KV at 100° C. of 2 to 6 cSt, 5 wt % to 90 wt % of a second paraffinic oil having a KV at 100° C. of 3 to 14 cSt and 5 wt % to 10 wt % of a polymethacrylate viscosity index improver.

What is claimed is:  
     
         1 . A hydraulic oil composition comprising: 
 (a) 5 wt % to 90 wt %, based on the composition, of a first paraffinic oil having a viscosity at 100° C. of between 2 to 6 cSt;    (b) 5 wt % to 90 wt %, based on the composition of a second paraffinic oil having a viscosity at 100° C. of between 3 to 15 cSt; and    (c) 5 wt % to 10 wt %, based on the composition, of a polymethacrylate viscosity index improver having a shear stability index in the range of 0 to 20    wherein the composition has a shear loss of less than 7% after 40 minutes as measured by ASTM 5621 and wherein for any given viscosity grade the composition has at least substantially the same or better Brookfield viscosity at 0° F. and −20° F. as a naphthenic oil containing hydraulic composition of the same viscosity grade.    
     
     
         2 . An oil composition according to  claim 1  wherein for each viscosity grade listed below the composition has the properties listed:  
       
         
           
                 
                 
                 
                 
                 
                 
                 
                 
               
                     
                 
                     
                 
                     
                   ISO15 
                   ISO22 
                   ISO32 
                   ISO46 
                   ISO68 
                   ISO100 
                   ISO150 
                 
                     
                 
                   Maximum 
                   −42 
                   −42 
                   −42 
                   −39 
                   −39 
                   −39 
                   −30 
                 
                   Pour Point ° C. 
                 
                   Maximum 
                    500 cP 
                   1000 cP 
                   1300 cP 
                    2600 cP 
                     6000 cP 
                    12000 cP 
                   22,500 cP 
                 
                   Brookfield 
                 
                   Viscosity at 
                 
                   0° F. 
                 
                   Maximum 
                   1000 cP 
                   2500 cP 
                   5000 cP 
                   12000 cP 
                   30,000 cP 
                   80,000 cP 
                 
                   Brookfield 
                 
                   Viscosity 
                 
                   at −20° F. 
                 
                     
                 
                     
                 
             
                
                
                
                
               
               
                
                
                
                
                
                
                
                
                
                
                
                
               
            
           
         
       
     
     
         3 . The composition of claims  1  and  2  wherein the viscosity index improver has an average molecular weight of from 10,000 to 1,000,000.  
     
     
         4 . The composition of  claim 3  including a minor amount of at least one hydraulic oil additive.  
     
     
         5 . The composition of  claim 4  wherein the additive is at least one of pour point depressant, antiwear additive, corrosion inhibitor, antioxidant and defoamant.  
     
     
         6 . A hydraulic oil composition comprising: 
 (a) 5 wt % to 90 wt % of a first paraffinic oil having a viscosity of 2 to 6 cSt at 100° C. and a VI of 85 to 95;    (b) 5 wt % to 90 wt % of a second paraffinic oil having a viscosity of 3 to 15 cSt at 100° C. and a VI of 90 to 95; and    (c) 5 wt % to 10 wt % of a polymethacrylate viscosity index improver having a shear stability of 0 to 20;    wherein the wt % are based on the total weight of the composition;    wherein the composition has a shear loss of less than 7% after 40 minutes as measured by ASTM 5621; and    wherein for each viscosity grade listed below the composition has the maximum pour point and Brookfield viscosities (BV) listed:                                                            ISO 15   ISO 22   ISO 32   ISO 46   ISO 68   ISO 100   ISO 150           Pour Point   −42° C.   −42° C.   −42° C.   −39° C.   −39° C.   −39° C.   −30° C.     BV, 0° F.    500 cP   1000 cP   1300 cP    2600 cP     6000 cP   12,000 cP   22,500 cP     BV, −20° F.   1000 cP   2500 cP   5000 cP   12,000 cP   30,000 cP   80,000 cP