This is not a super vs regular thread but....after searching Super UDT vs regular UDT I got to thinking does it really matter? Whatever you fill your tractor with it is going to get mixed in with the existing fluid in the FEL and BH thereby creating a composite fluid. I dont know how long it takes to completely cycle all the fluid through the machine or how much is in the hydo lines of the attachments but it seems to me that super and regular better be compatable. Since I dont know whats in mine right now I really hope this to be true. I'm sure it is, just like switching from conventional motor oil to synthetic doesnt require a thorough motor flushing. But hey what do I know I'm an electrician that spent to much time on eBay and now I own a tractor!
If either/both fluids are adequate I can't imagine that there would be an issue with mixing, blending, or otherwise allowing the dilution of one with the other.
They are, after all, each different blends from what is essentially same/similar base stock and additives.
Pump output can be found in spec sheets and is typically several gallons per minute, I would guess that (for the tractors that most of us have) total oil divided by pump output would show it goes around and is completely mixed in a small number of minutes.
Mixing/flushing out the cylinders of loaders and hoes is probably complete in half a dozen cycles or fewer.
Bottom line; it is all mixed up and has gone around MANY times when you have barely started the first project after an oil change.
You could figure the capacity of all cylinders on the loader and hoe, assume worst case of fully extended, hoses too, add 'em up and compare that to the total oil change volume. Then figure how diluted/polluted the new oil becomes from the old oil.
My guess is that you will have much better than 90% "fresh" and by the way the much less than 10% "old" wouldn't be harmful, just not quite AS good.
Unless you have somehow picked up several gallons of something highly corrosive I think there would be no point to performing flushing or multiple changes just to get the dilution factor down.
Now; How much brand name X hydraulic oil can be diluted by brand name Y before your whole tractor disintegrates before your eyes ?
That is a whole 'nother subject best addressed by the various brand name religious zealots (-:
