Scotty says highway miles are 10% of city driving. The question is if I did 60,000 miles of 99.5% highway miles, does that mean I only went 6,000 miles on my ATF, and I don't need to drain/refill?
Bear in mind that the 10% figure applies to mechanical wear, not to maintenance. No matter what kind of driving you do, the anti-wear additives in oil and trans fluid still break down. Ditto for anti-corrosion additives in coolant. Brake fluid still absorbs moisture, etc. I would not go 10K between oil changes or greatly extend change intervals on any fluids if you want the car to last.
That is technically true but if it were a CVT transmission or any say Nissan transmission I would still change the fluid
In my case it is a commuter Corolla S. Also I change the 0-20 Synthetic oil every 10k miles.
I’d stick to the intervals mentioned in your owner’s manual.