Originally Posted by bmweuro
The u-joints are the same on pretty much all BMW's produced after 1970, minus the new new bikes. The oil in the early bikes did more for the splined end at the rear drive.
While I don't disagree about being mostly for spline lubrication, I think there is more than a little oiling going on at the U-joint on the twin-shock models. I base this solely on the personal and anecdotal observation that I've never removed the rubber boot at the transmission output without having to dump a tablespoon or so of oil out of it. It had to get there somehow, and once there, probably provides some splash lubrication with bumps, jolts, etc. In my opinion, any lubrication in this application, even accidental (at least in a closed system like a twin shock swing arm anyway) is better than none.
The description "lubricated for life" is accurate. Bearings, joints and the like usually die through lack of lubrication. I'm sufficiently old-school to still want grease fittings on U-joints, ball joints, and bearing oilers where appropriate.