In support of Stuart I have to add that it was once commonplace to use "heavy" oil on a maintenance basis between strip down and re-grease. Following my Dad's example in the 60's I ended up using some from his spare bottle of (manual) gearbox oil (Castrol EP?) lying in the garage - but then you only neeeded to add a few drops to each bearing set (Cycling Manual quotes a few drops every 250 miles and an annual strip down). Thankfully Tecalemit nipples made it all the more easy and stopped most of the oil coming back out from where it was put in. Providing you stuck to few drops (or should that be squirts) and didn't leave your bike on it's side for too long, none would leak anywhere.
I guess at some point some sensible manufacturers boffin decided that so many owners ignored the maintenance requirements (or were blissfully unaware of them) between overhauls with little detrimental effect on the components that the lubrication holes were as well left off. Grease ? the only thing with soap in it that get's your hands filthy.....
As to the vegetable oil 'Castrol-R', now that is smell from the past once overheated (best of all in a Cosworth BDA or BDG engine. But that's another subject / list......
Bob Reid
Stonehaven
Scotland.