Liquid grease for gearbox

Some gearboxes run on semi-liquid grease. My Enfield Bullet's gearbox for one. I don't suppose running an AMC box on appropriate grease will do it any harm but where oil is specified, who not use oil?

I use EP90. 200,000 miles on my 99's gearbox with only a layshaft bearing failure. And the odd return spring. 

Semifluid grease was used in many prewar gearboxes. Still used in a few gearboxes after the war. My Vincent Comet, which has a Burman gearbox uses Penrite semifluid grease. The advantage is that the grease component seals the leaks while the oil component lubricates the gears and axles. So using it instead of oil keeps the gearbox almost (but not fully) leakfree. A Norton gearbox is designed to run on oil with (almost) adequate oil seals. The original spec engine oil can be replaced with an 90 weight gear oil which has about the same viscosity. My TTI gearbox uses a synthetic 75/90 oil as recommended by the manufacturer

Edit: To get semifluid grease into the box, warm the bottle in boiling water.

I read that the issue with the "Norton" box with semi grease was the kick start pawl not returning when left cold. No experience of it but something I had read...

 I cant imagine it "flings" that well when cold either, being a "splash" lube system it may take some time to coat the relevant surfaces.  

Jon