Transmission oil

Hello, I am wondering if the transmission oil for the 2014 frs needs to be oem? I’m new a new owner of a frs and my fathers telling me not to use any other transmission oil other than oem from the dealerships mechanic. They quoted me $650 cad for the transmission oil change. I looked at some videos online and it seems not too hard to do myself. So if y’all can recommend me a specific transmission oil that’s good and reliable on the car that’ll be great. Thanks!