Today I've had the transmission oil changed in my Range Rover Sport 3.0TDV6. I'm sure the Transmission oil has not been changed during its 12year and 114,000 mile life so is well overdue.
I opted to have a Megaflush, which replaces around 99% of the transmission oil.
The video goes through the process and also fluid changes to the Transfer Box and both Front and Rear Differentials.
This particular flush does not use detergents, only oil.
I'll post in a few days after some use as to the difference it has made.

The legend that is Bodsy! He did mine (coincidentally, same model year and near identical mileage) a couple of weeks ago. Gone: 10MY L320 RR Sport HSE, Ipanema Sand
Gone: 20MY Jaguar iPace HSE, Silicon Silver
Gone: 17MY RR Evoque SE Tech, Loire Blue
Gone: 08MY Discovery 3 XS, Stornoway Grey
Gone: 07MY FFRR TDV8 Vogue, Stornoway Grey

He certainly knows his stuff.
Looking forward to taking it on a run over the weekend to see the difference it has made.

Mine was noticeably smoother after the work. I also had the diff and transfer case oils changed. Gone: 10MY L320 RR Sport HSE, Ipanema Sand
Gone: 20MY Jaguar iPace HSE, Silicon Silver
Gone: 17MY RR Evoque SE Tech, Loire Blue
Gone: 08MY Discovery 3 XS, Stornoway Grey
Gone: 07MY FFRR TDV8 Vogue, Stornoway Grey

He's doing my second Megaflush next week at 140K miles
First one was done at 83K in 2019
Legend  Visitor from fullfatrr.com
* GONE. 2012 RR Sport HSE SDV6 Orkney Grey. Now being piloted by RRSTDV8
* GONE: 2011 4.4 TDV8 Full Fat. Amazing piece of kit.
* Current. 1974 Lightweight 2.25L petrol. Old skool
* GONE. Freelander GS TD4 Manual MY2013. Orkney Grey with privacy, cold and clearview packs, armrests (a must!) and a spoiler.
* GONE. Range Rover Classic '93 200Tdi Factory fit
* 1949 80" in family since 1975