Trying to bring some clarity to the thread, which has drifted off into rear-drive-oils:
1. BMW Spec'd SAF-XO which was unobtainium in the US.
2. So BMW then spec'd their GL5 75W-90 synthetic oil - which is red (probably a dye) in color. Almost everyone got this at the first rear-drive oil change (if you were lucky and the dealer did it at the 600 mile service.)
3. For a while - someone (I think it WAS BMW from talking to my parts guys) offered the official Castrol SAF-XO oil in Castrol packaging. It was expensive - around $45/liter. That showed up at my dealer and talking to the parts guys - they never sold ANY of it retail due to the price. They may have used it up on service bikes.. dunno, but it's now gone. That was BMW's MSRP on it.
4. Suddenly! Appearing on the oil shelves of my dealer was a BMW branded oil called C-SAF-XO 75W-90 GL5 oil. Given the "C" in the branding - my WAG - it's the same oil they were selling for $45/liter - but it was now priced a reasonable $25/liter. I bought some. I haven't opened mine. So I dunno what color it is.
5. People have bought the Castrol SAF-XO oil from Land Rover dealers - and report it cost about what #4 above cost, and was an amber color (no dye.) FWIW - Porsche spec's the same oil in differentials for my Cayenne - but everyone in Cayenne world uses Mobil-1 gear oil, with great success.
My conclusions: (Some* stolen right from Paul Glaves)
1. Some oil is better then no oil.*
2. Either the original spec'd oil (the SAF-XO stuff) is good, but the BMW 75W-90 GL5 is likely equally as good.
3. Clean oil is better then dirty oil.*
4. We obsess too much over magic elixers - but there isn't any real harm to it except for the shelf of "old oils" in my garage, ones formerly thought to be the magic potion, then cast aside in the glow of a new Interwebz discovery.
Anyone want a partly used bottle of BMW GL5-Synthetic? I'll make you a deal..