There seems to be a lot of confusion regarding what oil types to use for the transfer case (TC) and differential (diff) oils.
I read a post where it says the Mini dealer used 75W-90 oil for the TC. I've never seen such low viscosity (thick) oil used on a TC. My Mercedes vehicles used the same type oil as the transmission. My Land Rover uses an oil of "similar" viscosity to the transmission fluid. I doubt that the Mini would use such heavy oil for the TC.
For the front/rear differentials, Mini apparently says to use a 75W-85 Hypoid axle oil, which makes sense.
Other posts seem to indicate that the TC shares the oil with the transmission.

Does anyone know for sure which oil types are used? Do the manual and automatic transmission Countryman S All4 use the same TC?

Thanks!

 

If it was me, knowing how the X3 transfer box is sensitive to the custom (and secret) mix of friction modifiers in 83222365987 which can lead to a $3000 transfer box failure, I'd just spend the money and buy the genuine BMW fluids.

Its not like you have to buy it often enough to be pinching the pennies and it's only about $70 for a bottle and the peace of mind.

 

Thanks.
So what you're saying is that the TC uses a 75W-90 weight oil? I don't mind purchasing the magic fluid but I'm concerned it seems the incorrect oil weight for a TC.

 

FWIW, years ago I would use Redline Heavy Duty Shockproof in my xfer case (different car), so I wouldn't really worry.

 

That BMW PN on Realoem.com looks like the same magic fluid across all transfer boxes.

 

I recall (from seeing some specs a while ago) that a 75W rated gear oil is not very dissimilar in actual viscosity at (for instance) 0C temperature to a 10W rated engine oil. For instance see this from Wikipedia:

https://en.wikipedia.org/wiki/Gear_oil