I think I read this trans calls for 70/80 from mb but was curious about mixing to get the best of both worlds. for example gm synchromesh is considerably lighter so if I went 1.7L factory to 0.3L synchromesh............I am assuming once it heats up they would mix bringing it to like a 63/75 or something but when it sits and is cold would the lighter oil separate and go to the top?

i.e. when cold it would be utilizing the lighter oil since it is on top then mix with the heavier oil when warm??

thanks in advance