I recently had my transmission flushed (12 quarts) and refilled (4quarts) with synthetic transmission fluid (they didn't tell me they were going to use synthetic).

Anybody else using synthetic transmission fluid?

 

I use Amsoil synthetic ATF, which complies to Toyota T-IV spec and works well in Aisin Warner transmissions. I have driven my RX ~5000 miles with Amsoil, so far with no shift problem, just better protection and better upshift. Do not use Mobil 1 Synthetic ATF, it does not comply to Toyota T-IV.

 

RedLine D4(according to their tech support department) is also compatible with Toyota Type IV transmission fluid. Just switched to it and noticed slightly smoother shifting. You can also use Mobil 1.

http://www.mobil.com/USA-English/Lub...l_ATF_3309.asp

 

Please do not add confusion by your own mistake/typo.
Mobil has TWO products, Mobil 1 Synthetic ATF is not T-IV compliance, Mobil 3309 ATF is.
Mobil 1 Synthetic ATF is not friction modified for Aisin Warner transmissions, Mobil 3309 ATF is.
There is a BIG difference.