Transmission hard to shift --> OIL??

["Michel Drainville" <MDrainville@xxxxxxxxxxx>]

Car: 1991 318ic ; 106000Mi

My tranny has always been hard to shift since I have the car (4 years).
When I bought the car, I flushed the tranny and filled it with Castrol ATF
DextronII as per BMW instructions.  Last year I tried another car identical
to mine, and the shifter was moving like in soft butter.   At the time I
tought that may be my clutch was faulty since on occasions it was slipping
a bit.  So , this winter I changed my clutch with a BMW unit. At the same
time, I changed/cleanded/lube all pivot points of the shifter.  Now I have
the car on the road again, the shifter feels the same.

I was wondering if some specialized oil, friction modifier stuff, could
help my tranny.  Do I need something to reduce friction of the synchro or
raise the friction rate to the synchro so they spin less??
Hopefully I'm not due for a rebuild.  If it's the case, is it better to
rebuild (synchro only?) or buy a used one from a more recent car?
What is the lifespan of these tranny? Getrag40?

Thanks
Michel Drainville
91 318ic

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