this is why early Harleys (Flatties, Knucks, Pans and Shovels) did not leak oil because of “bad seals or poor workmanship quality”. The primary chain has an oiler circuit coming from the oil pump. It’s adjusted to a drip rate of 2-3 drips every minute or two. Once it hits the rotating chain, it lubricates and gets slung off. It’s done its job. The inner primary cover has a factory drilled hole at the low point for it to drain. These bikes had dry clutches. With later wet clutches, this was no longer required.