My next door neighbor is the general manager of a John Deere Construction equipment dealership.
The last time that I changed out the Lo-Vis Hy-Gard fluid in my 425 AWS, I mentioned to him trying to find a substitute for it... he immediately responded with "Don't do it".
If there were some sort of an acceptable substitute out there that he knew of, I know that he'd tell me. I mentioned ISO 32, and he waved it off, and said it is not the same.
He told me that the Lo-Vis Hy-Gard is actually a semi-synthetic blend.
He had no financial interest in this, as I was only going to be buying 6 quarts, and the smallest amount that he could sell me would be a 5 gallon bucket.
I paid a little over $4 a quart for it at the JD Ag dealer. Considering that I pay the same amount of money for a quart of semi-synthetic Pennzoil for my truck, I'm not going to complain about what John Deere charges on this.
Of course, finding it on a Sunday is still going to be an issue...