Cooper man, I'm fully with you re. the nanotech+ millers oils and also use them in my engine too! the difference is very noticable!
Interestingly BTR recommend 75W-90 in their axle's with no difference in grade except for friction modifier for the LSD variant yet Morgan list it as 80W-140 non LSD. Like wise with the Durance engine oil 2006-2014 Morgan state 5W-40 oil yet Ford recommend 5W-30 as a first choice oil. Perhaps here Morgan should explain why they chose these alternatives over manufacturers listings. I thought that perhaps for the engine the slightly thicker oil might be to deal with the engine situation and that it ran hot because of the cooling issues appertaining to fitment.
The Diff I can find no explanation for. There is no workshop manual available for the Morgan adaptation/fitment so owners who are a bit hands on go for the manufactures type options and their fitments where they find differing information and this creates confusion. I figured that it might be the fact that in the Morgan there is no turbo so they raised the viscosity slightly to keep oil pressure up when running hot! Shoot me down if you like! or Perhaps a Morgan person might come along tell us all and let us make informed choices. We know the BTR axle was a rush decision by Morgan as when the salisbury axle finished production Quaife had offered to supply axle parts to enable Morgan to continue fitting them but no response came from Morgan so the Australian Holden pick-up axle was its replace meant. yes that"s the one with the built in end float!
In my book, it’s 5w30 with semi synthetic oil or 5w40 with fully synthetic.
