I have a nice Clausing-colchester vari-speed 13" lathe that has weeped out a bit of lubricant over the past several years, and has reached the point of needing to add some more. The manual recommends Shell Tonna 33 and Tonna 37 for the Gearbox and headstock respectively, and yet another for the apron.
Looks like they're not made anymore. What's the appropriate oil to use as a replacement? What Quantities am i looking at as well? it's not listed on the lube chart. Finally, does it make sense to drain and refill fresh on a regular basis, or just top off?