[QUOTE=Grand Bois;10267133][QUOTE=BCRider;10265779]OK, I'm going to sound like Operator here and say that this is positively the worst suggestion I've read on this forum EVAR! There's simply no guarantee that the oil would actually reach the bearings without it running out the likely drain hole in the BB shell. And if it turns out to be a sealed cartridge BB then the oil wouldn't even see the bearings. And even if there is no drain hole or he pours it in quickly enough it would take the better part of a quart of oil to fill the BB shell AND the lower portion of the downtube AND the chain stays before it actuall reaches the bearings. I have yet to see a frame where at least the downtube is not joined into the BB shell with openings to allow the air pressure to equalize during welding. And pretty much all lugged bikes have openings into the chain stay as well. At the very least this will create quite the oil puddle and at worse it won't achieve anything.
But you're completely wrong. It's the way that bottom brackets were lubricated for decades. There are still lots of bikes on the road with oil fittings on the top of the Bb shell. My '59 Carlton has one. Some bikes required that you pour oil down the seat tube.
I have no idea what this is supposed to mean:
"I have yet to see a frame where at least the downtube is not joined into the BB shell with openings to allow the air pressure to equalize during welding."
It originally had a metal oil cap like on a Sturmey Archer hub. I stuck a zerk in it just to fill the hole. It's just for looks, since it has a modern cartidge BB in it now.
My thought is that since there are openings from the BB to the chain stays and often holes in the chain stays, that the poster felt that most of the oil would run out before it could adequately lubricate the bearings (assuming it could reach them at all). I'm not sure I agree with that point exactly but I don't think pouring oil down the seat tube would work with this bike anyway.