The trouble with those alternative oils is finding them. At one time you could go to a gas station and perhaps pick up a container. Stations today are more interested selling coffee. At any rate, I tracked down a supplier and by the time I got it here, it was more expensive than the Mahindra oils with its pricing (Chevron) about the same as Mahindra. It was simply easier for me to take the 10 minute ride to the dealers and plop over the $85 per 5 gal. container. Is it the same as the $45 Tractor Supply stuff? I dunno, but for the sake of the warranty, I wanted no excuses. For the time it's gonna take for me to get to the next oil change ( 4 or 5 years) I'll spend the extra.
As to the extent of hydraulic oil changes for my type of use (lucky to put on 60 hrs in a year) I changed out the hydraulic oil in my old tractor (JD-750) 3 times in the 28 years I had it. Never a glitch.