Greetings,
It's so funny to recall things through the sense of smeller perceived sense for that matter.
As the famed American baseball quotemaster Yogi Berra is claimed to have quoted "nostalgia is not what it used to be"
The smell of Castrol R being emitted down the megaphone of a Norton brings back the 60's when you could just go out and ride your motorcyle, no body bothered you provided you showed respect but in reality I guess that I was still regarded as just a young tearaway.
Castrol R was a great oil in its time in its own way but it had its problems too, it would coagulate if not changed regularly, if you inadvertently mixed even a tiny amount of it with the new fangled multi grade oils it would block the oil ways to seize the engines, with a new engine it would leak past seals until it had built up a layer of shellac,
oh yes it was great stuff
Lubrication is still a nightmare subject and although we tend not to have the leakages we still have the inability for oils to be mixed or incorrect specifications used. There are some engines that must only be run on the manufacturer's specification as anything else will cause failure. So be careful as to what you put in the crankcase or where ever, what works for one may not work for another.
Oh, yes motorcycle oils are different to car oils so don't mix them up, especially if your clutch and gearbox are combined.
Still love that noise and smell though, despite the problems
TTFN
Hugh.