Need help in understanding & correct choice of MTF

[dailydriver]

MolaKule;

What would be the net result/(negative??) effect of me using the MT-90 in the T56, instead of the MTL, or D4 I am currently using??

Does gearbox wear on a 160K mile old unit have ANY influence on which viscosity should/could be used?

Is there a viscosity point at which synchro/blocker ring design will just not work, or become 'balky'/un-shiftable, regardless of gearbox wear and tear????

 

[MolaKule]

Originally Posted By: dailydriver
MolaKule;

What would be the net result/(negative??) effect of me using the MT-90 in the T56, instead of the MTL, or D4 I am currently using??

Does gearbox wear on a 160K mile old unit have ANY influence on which viscosity should/could be used?

Is there a viscosity point at which synchro/blocker ring design will just not work, or become 'balky'/un-shiftable, regardless of gearbox wear and tear????

That's almost impossible to answer except to say that as a rule of thumb, gear box wear would require a slightly higher viscosity, say a 1 to 5 cSt increase.

If the tranny is shifting ok, I would stick with the MTL70W80.

If the synchro/blocker ring becomes so worn that gearing doesn't synchronize, then it is time for a rebuild.