If it is, then add Toyota to a long list already occupied by Honda among others. (Does this mean it wouldn't be heresy to pour Honda motor oil into a Toyota engine?) Seriously, though I'd bet its either Drive Clean 5000 or Exxon Superflow. It just doesn't make economic sense that whoever bottles these private lable oils would further dumb down a fully formulated entry-level blend that still has to meet "SM"/"GL-4" standards. The extra cost of maintaining alternate storage and blending facilities, seems to me, would outweigh any potential production cost savings. I could be wrong, though.