If it's a manual then it is more than likely caused by a clogged vent line. If it's an automatic and discharges a large amount of fluid in a short amount of time while running then it is probably a transmission cooling line.
Automatic transmission fluid would likely cause a standard transmission to overheat and wear the gears at a high rate.
Not changing the transmission fluid in a car within 200K would cause problems.
The most common cause for a transmission not to change gears, is low transmission fluid. Check the transmission fluid and fill to the full line.
Stripped transmission, low transmission fluid.
You hit something and busted it open
yes it would cause the gears to slip more or less
Leaky transmission lines would cause the fluid level to drop and eventually cause the transmission not to shift and go.
Your motor oil going bad would cause that. That is in the crankcase, not the transmission.
1. Low transmission fluid. Check this first. 2. Old transmission fluid and clogged filter. 3. Worn clutches inside transmission.
Is your transmission fluid full?
The most likely cause would be low fluid level.
No, but it could cause higher then average wear on the transmission.