So I have a client that is asking about if they should switch from one lubricant to another in a planetary gearbox they have.
The main advantage that this new lubricant has is that it has a much lower viscosity (about 1/2 as much) and it is more thermodynamically stable.
With all things being equal, I'm looking to try to get a rough order of accuracy estimate for the efficiency increase in switching to this new lubricant. I've been looking through some hydrodynamic lubrication theory, but haven't found anything that is really what I'm looking for.
Any known references or established theories related to this would be extremely helpful! :)