I just bought a 2015 GX 460 with 98k miles. The service records show it's been serviced by Lexus dealership every 5k miles. I was going to do a transmission drain and fill, but looking in the owners manual, it doesn't call for this service at any of the service intervals. Should I be performing this, and if so when? Also, I noticed that Toyota's say transfer case. Is that referring to the automatic transmission?
There is no such thing as "lifetime" transmission fluid, it needs to be changed regularly no matter what Toyota/Lexus says. It should be safe to do so with only 98K miles, though 40K-60K change intervals are commonly recommended for most vehicles.
If you have a transfer case you must have all-wheel-drive, that's what controls power delivery to the front and rear wheels. I don't know if it's integral with the transmission on that vehicle. If the transfer case is a separate unit that will have fluid that should be changed as well.
I think lifetime would end up being a limited lifetime.
Like chuck said every 40 to 60 thousand miles is good. Always change and never flush.
