It sounds like your speed sensor is going bad. It sends a signal to the speedometer to display the correct speed and sends a signal to the transmission on when it should shift.
What is the fluid capacity of a Toyota Corolla automatic transmission 3.3 Qts drain and fill
You need to replace the speed sensor. It sends a signal to the speedometer and also sends a signal to the transmission on when it should shift.
on the transmission. and it requires gear oil
You go by the manufacturer's recommendation.
Your owners manual will tell you.
If it is an automatic transmission every 30 thousand miles.
sounds like the cable broke usually on the transmission end
1995 Toyota Corolla automatic transmission won't go sin any gear
every 50,000 miles if it is an automatic trans.
It would be cheaper to repair or replace the automatic transmission. There are too many differences between a standard transmission and an automatic to economically swap in a standard.
Most speedometers are run off of the transmission. Something was not correctly put together.
It has no differential plug.