i do a blend of 25%bar oil 75%clean oil drained from qt and gallon bottles of 5,10,15 wt and or any atf bottles , drain all bottles for a couple hours ,into a gallon bottle takes me about a month to get a full gallon [ doing 3-4 oil changes a week in my shop] end up buying 3 gallons b/c oil per year yields 12 gals special blend . i use the most in the spring during firewood processing so i sometimes run a little low and it takes the rest of the year to rebuild my stock pile . works for me jk