I just bought 2016 RR Sport Supercharged 5.0 V8 (GA597312) with 57k miles and 90 days of limited warranty from Autonation.
It seems rear differential oil (every 5 yrs needed) was never replaced. Need help with two things:
1. What oil is LL recommended for this application? And how can I verify that by myself? Owner manual has only engine oil info. VIN web search is very unclear about fluids.
2. Is a seller (bmw dealer in my case) responsible for such missed compulsory maintenance? The given warranty doesn't cover cases if the vehicle was not maintained accordingly. So, any dif issues automatically withdraw and it worries me a lot. There are also missed transfer case oil, spark plugs and supercharger belt replacements.

Appreciate any advice on it.

Do you have a open rear diff or a electronic locking one ? as they use a different spec oil in each.

I think you would be very lucky if any dealer would accept responsibility for previous missed service item's on a used vehicle, that would be down to the previous owner not having it done I would think.

Cheers
Col