Each cam bearing has an oil feed hole, the #4 cam bearing has 2 holes, the second one goes upward to feed the rocker arm shaft.
The SL6 design engineers were pretty clever, they actually have the main bearing oil feed cross-hole breaking-out, into the block's cam bearing bores. Basically, they drill one hole and it feeds the cam bearings and the crank bearings.
The down side to this design, installation of the cam bearings tends to 'pinch down' and restrict the oil flow in that area. I do a good amount of inspection & oil passage rework in this area, in order to insure good oil flow past the cam bearings and down to the crank where it is needed the most.
DD
