For the record I use Rock Oil SVI http://www.rockoil.co.uk/
from CRC (and there is somewhere near me that sells it)
Plus it's good enough for TFTuned
They say the rebrand for others so is probably under many other names.
It was cheap and works plus they have a large weight range so I can blend if needed (or run out of one by a little bit
Since I do RockShox and Bombers I have 5 and 7.5 but need some 20 for some XCR (same as XC600 but bolted together differently I think, but I cannot separate the lowers.
Both work for me in their intended weights.
But now you have me idly searching
another table, but with Rock Oil in (or at least easier to read)http://transmoto.com.au/comparative-oil-weights-table/
Still who knows what the oil viscosity was like 15/20 years ago. No doubt there are more/different additives and whatnots in the oils now.
(still xc600 where using 20wt, when the other Marz forks where using 7.5wt and RS Mags where using 8 and 5 wt )