I read the post from Dave Zechhausen and a rep from Royal purple on Bimmerfest, extensively. according to them Syncromax is a direct replacement for LT1 or LT2. Which accordin to Royal purple are transmission based lubricants. The diff is gear oil in mine i belive. This is what Dave puts in his BMW race cars.
After a chemical lab analysis of The BMW fluid there was was nothing special in it or any of BMW fluids which apparently are similar to Castrol Syntec products. I chose Royal Purple because I thought it best. I just wanted to not pay the $90 for supposedly "off the shelf" castrol fluids as I was told.
here's royal purple cross reference for the most common auto manufacturers.
I even had my mechanic friend's blessing to use it, sayin it was a "superior" product.
BTW...IF you or anyone is interested in the chemical analysis of the BMW fluids...I can dig it up once again