Is this lip or shelf on the inside of the edge of the cover supposed to serve as a "guide" of where to place RTV?
That trough is there to "collect" the RTV that squeezes out as you tighten the bolts down. If you just have two flat surfaces with even edges, the "excess" RTV will form a string that can easily pull off. Then that string will wind up in the oil pickup. The trough provides more surface area for the excess RTV to stick to so it can't come loose. More of a pain to clean up on a reseal, but less chance of engine problems. Posted via the PriusChat mobile app.
