Its time to change the diff oil but I am confused as to which oil to use in my BTR diff. The handbook says "HD 90/SAE 85W90, but the bible says 80W 140(p.103). If it is 85W 90, can I use 75w 90 or 80w90, as I can't find 85w90? Don't want to balls it up!!
That's the viscosity range to use, yes. The OEM recommended product was a fully synthetic Mobil product that is no longer available; the Morris one is apparently done to the same formulation
