Recommend synth fluids
 

I am planning to change both the front and rear diff oil and the oil in my 6 speed trans. What do you recommend (brand, weight) for each? Redline?, Royal Purple? Amsoil? What has worked well for you? Thanks

Royal Purple 85w90 in both differentials for me.
If you live where it doesn't get too cold and tow heavy use 75W140

I don't have a 6 speed, rather a 5 and use the only lube the factory recommends, Castrol Syntorx (not Syntex), which is also a synthetic.