I'm going to install a hayden AT cooler on my 2003 4runner.At that time I was thinking to change over to syn. ATF. What syn. ATF is compatible with the stock Toyota fluid. I'm not going to get all of the stock fluid out. I figure about 80% or so.Amsoil,Castrol and Valvolne are the ones i'm looking at. Thanks in advance for the reponses.

 

The ATF for my '87 4runner is dexron , now the brand that i want to use is my choice. Same goes to you, find out what kind of ATF is needed for your truck then decide what brand you want to use.