I have a newly acquired 2017 420R SV with what I guess is the BMW LSD. I am changing all the fluids so I know what is in there and especially following this thread see that new Diff oil is a good idea (it is a little noisy) but Caterham are now suggesting a different spec (75W-140) to the cars handbook (EP80W90) and there seems to be little consistency of what to use on various forums. Can anyone give me their view (and why) - my car use will be split between trackdays and touring. Much appreciated !