Is blue color and can be mix whenever BMW dealer had installed about two years ago?

 

I used the ATE SL.6. It is not tinted, so it is very lightly yellowish. It is not the ATE Super Blue. The idea of Super Blue is to more easily tell when you have the new fluid coming out. You can alternate flushes between the natural and Super Blue. But, SL.6 is lower viscosity and that may be slightly better. The Bentley manual says that Low Viscosity DOT 4 is preferred. You can mix low viscosity and normal. If you are in Florida, Super Blue is not street legal.