I have seen this oil problem on a small handful of motors.... Never found a solution to it....

All the lifters manage to die on one bank of cylinders, due to some blockage or something somewhere.... that typically shows up after doing work on it only.... to my knowledge I have never seen this issue pop up randomly while the car was assembled and running.

I also have never had a chance to troubleshoot this problem personally, it was all over the internet/phone every time I have ran across it.