I am going to change rotors and pads on my 03 Sorento to slotted and drilled rotors with the pads they recommend. I am also going to give it a fluid drain and fill. It has been suggested I replace the fluid with Dot 4 fluid. Factory shows Dot 3. The truck has 4 wheel discs. Good idea? Synth ? Best brands? Thanks for you knowledgable answers in advanced.