1994 Toyota Corolla Q&A

1994 Toyota Corolla Question: Toyota corolla 94 overdrive problem when car temprature low

I have toyota corolla 94 auto transmission with 148000 km drives well exept when i drive car on freeway and car temprature goes down gear automatically change and rpm goes high. I change oil but situation still same. When temprature needle bit up gear shiting correctly -
Answer 1
If the engine is not warming up to operating temp. and staying there , then possibly the thermostat is not functioning properly. -
Comment 1
Dear Zeptie You are champ car is fine now. you were right all mechanic advice me to change transmission but it was only thermostat. Thanks -