MolaKule:
saying RL MTL 75W80 you mean MTL 70W80 ?
due to your answer to my 1st question I reason:
- friction is important for the synchronizers
- viscosity for forks and rods
How does the tribologist decide the best viscosity scope for a gearbox. Providing that he determined the correct visco range, isn't it not careless to leave the range e.g. in order to improve the cold shiftabilty, while on the other hand e.g. the forks wear out more. In other words: May / should I trust in the manufacturer oil visco recommendation as best compromise ? Dave from RL told me to go not too far from recommended visco. In my case I think to go from 75W85 to 70W80 is not too far, isn't it ? 75W85 --> ATF would be too far !!
My problem is most of the fine oils discussed and recommended here (pennzoil, amsoil, RP) are not acquirable in Germany. The only available is Redline.
to your 2nd answer:
the ticker the oil film is the less often the EP/AW additives must prevent the worst, isn't it ?
btw: in hot temps when the oil is more slurry, in this case isn't the centrifugal force of the rotating gears a issue in respect of the adhesion of the oil ?
Does friction value of the oil decrease with increasing temp ?
a lot of questions to specialist, thanks a lot !
Gear oil is a very interesting subject for me