Got to be careful using ATFs from other vehicles. I noticed something when looking to find out what to use in my Aisin AWF8F35 8-speed unit in a 2019 Tiguan, which happens to be the same transmission as in a 2019 Toyota RAV4.
For my Tig, it uses a slightly higher viscosity ATF "VW G 055 025" than the RAV4's Toyota WS. The WS spec is similar to Mercon LV (LV = 'Low Viscosity') or Dexron VI, all lower viscosity.
VW wants to spec the lowest viscosity ATF that it can, for EPA MPG reasons, yet they spec more visc than an LV (or ULV) ATF fluid like in most other vehicles.
That may be due to the different peak torque the AWF8F35 endures hooked up to different engines. The RAV4 has 18% less torque than a comparable '19 Tiguan like mine, so the RAV4 can get away with a lower viscosity for less load bearing capability where hydrodynamic bearing & gear conditions occur inside.
In other words, VW knows the Tig will lug down low at higher torques more than a lightly-loaded RAV4, even though both use the same AWF8F35 tranny. You may never notice a difference if you use a Toyota low-visc fluid in a VW higher-visc application since there is some margin built in though. Still, VW felt like it had to go thicker for a reason.
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That said, I only have references from ECSTuning.com, RockAuto.com, and Amsoil.com, which all say use G 055 025 (A2) ATF in a '19 Tiguan, so I'm assuming that is the right spec for me. That's a kv100 of about 7.3 in an MQB Tiguan, vs. 5.5 for RAV4 ATF.
Does anybody have fluid specs for a '19 Tiguan for the transmission, transfer case, rear differential, & AWD unit in the back? Guess I may need to get a service manuals to be sure. It's good to know to double check what a dealership puts in, since they are known to guess & mess it up from time to time.
