Gearbox oil

Hi what oil are you chaps running in your gearboxes . It only mentions steam engine piston oil in the hand book. 

Hi Cliffy,
           There is a substance on the market called grease-oil, perhaps not much different to your quoted steam piston oil.
A problem is the indifferent sealing of the gearbox: any truly fluid oil, however thick, leaks! I use SAE 250, it's like treacle, but it still oozes out.
Grease-oil, I think, becomes fluid when squeezed between gear teeth, but otherwise remains scarcely mobile. Ideal, but expensive, I expect. 

I have installed oil seals on both input and output shaft so should be oil tight. Will look for some grease oil but may try some 120 grade to make the gear change easier when cold.

I wonder if this one fits the bill, it's called Castrol L/EPO, and claims to be a "semi-fluid self-levelling grease for veteran and vintage cars and motorcycles with grease-packed axles and gearboxes".
Worth a try? (If it's good, don't forget to let us all know!)

I rebuilt the  gearbox on my machine last year due to a slipping fouth gear and also to try and cure the gearbox oil leaks. When I recommisioned the gearbox I used Penrite T250 Transoil SAE250 gear oil which seems to have done the job. Gerachanges have become alot less "cruchy", but I have been practising alot too.