thanks for the info.i was under the influence over filling would cause damage.i have been taught over years not to overfill because it causes damage. i guess it does'nt in every case. also its nice to finally chat mr. 14,436 post man. i've read alot of your posts and learned alot.
thanks bill 302
Bill, thanks for the kind words but post counts dont always mean the person knows what he is talking about (as is the case for me. ).
The fluids do heat up and expand with heat (all hydraulic fluids that I know of, do expand with thermal input) but the fluid level in a manual trans is not near the top of the case (so there is room for expansion).
Now there could be undesirable parasitic side effects or some sort of enhanced shearing (I really dont think the latter is a worry). I dont see an issue myself but I dont design trannies.