I have a 2006 Scion XB 1.5 L4 with a used 6,000 mile used  L4 automatic transmission that is being installed to replace my 178,000 mile L4 transmission that drove 22 miles and had no engagement in drive or reverse after replacing the engine. So I bought a really low mileage used scion L4 automatic transmission that had the fluid drained when removed at salvage yard, so I have to refill the fluid and my question is besides the TOYOTA ATF type T- IV  what else is better now to use? I know that this ATF type T- IV  is a German formula but that is from 2006 and now there are many newer types of full synthetic that are more advanced in cooling as well as function, and  synthetics that are "middle of the road" so they can state that many different car models can use their fluid. I have seen too many replies of just stick with Toyota ATF type T- IV but nothing from transmission shop experiences using a "better" synthetic fluid.