Ed Huntress fired this volley in
:

To reduce friction against the cages and against each other, in
cageless sets.

Really? I didn't know that! not

And why would one lubricate the rollers in a garage door track? Because
they do not roll precisely-true, and rub on the sides. And they're
noisy, metal on sheet metal, and all that; lubrication also quiets them.

Just to be clear, Ed; I knew all about that... its being sort of
"mechanics 101". The joke about BLO and graphite was a joke, so "off-
the-wall" that ANYBODY would have 'gotten it'. And so many didn't...
sigh

Lloyd