I used some for a while. Not cost effective, but it had plenty of ZDDP, so I liked it for the Bug and the old slant-six. Rotella/Delo 15w40, or Rotella 10w30 of you don't want to use a 15w40, is mucho more cheap, readily available, and has decent enough ZDDP.
EDIT: I think Delo actually dropped their ZDDP levels, but Rotella was still hovering around 1000 phosphorus last VOA I saw.