I had my transmission fluid changed this summer and my Hyundai guide instructed me to have the fluid changed at around 60,000 miles. I check with the shop that did it and they did verify that they used the Hyundai transmission fluid. My car was driving fine until about a month ago when I noticed hesitation occurring at 40 mph. I may go 5 miles over the speed limit but not fast enough to stress the engine. My car is an automatic so I don’t have a hand in changing, except for when I step on the pedal.