So I have found with the Land Cruiser and LX570 fanboy group, there is a certain mystique about the vehicles. Although they are VERY well put together in comparison with lets say a Gm Suburban, they are not without some very expensive "faults", and they are in fact a conventional car, nothing different. On another forum: www.IH8MUD.com they refer to some of the special fluids as "Unicorn Tears". Being as the Toyota juice is $60 bucks a quart. Which is ridiculous.That's what I thought. IIRC circa '14 with the Gen 2.5 Tundra they started calling out the single weight? 75W? I think
I used the Amsoil MTF in a '15 Tundra and the owner claims it really does go into 4hi more readily (something I read online but didn't believe)
Even so, you hear plenty of anecdotal claims that a Toyota dealer will just pump 75W90 in there and call it good
I think after 2010, they switched to another fluid, which even Amsoil does not have a replacement for......Redline does however, 75w85 gear oil.
In short, there is a chain shafts bearing gears and seals, not unlike any other Tcase. Mine calls for GL5 75w90.
I change the stuff regulaly anyway so I dont really sweat the brand.......but if I am not using a regular brand like M1 or Valvoline, i would much rather give my money to HPL than Toyota.
AHC fluid is a different story of course, although i wonder why some do not make an equivalent.