Patent ID: 7569524

Claim:
A process for making an ashless hydraulic fluid or an ashless paper machine oil with high oxidation stability, comprising: a. hydroisomerization dewaxing a waxy feed having greater than 60 wt % n-paraffins and less than 25 ppm total combined nitrogen and sulfur to make a base oil having greater than 90 wt % saturates, less than 10 wt % aromatics, a base oil viscosity index greater than 120, less than 0.03 wt % sulfur, and a sequential number of carbon atoms; b. fractionating the base oil into different viscosity grades of base oil; c. selecting one or more of the different viscosity grades of base oil having: i. a selected base oil viscosity index greater than 150, and ii. greater than 35 wt % total molecules with cycloparaffinic functionality; d. blending the selected one or more of the different viscosity grades of base oil with an ashless antioxidant additive concentrate to make the ashless hydraulic fluid or ashless paper machine oil; wherein the ashless hydraulic fluid or ashless paper machine oil has a viscosity index between 155 and 300 and a result of greater than 680 minutes in the rotary pressure vessel oxidation test by ASTM D 2272-02 at 150° C.