My Buick went crazy 2 days ago, the car won't move if you transit to overdrive from neutral, though the RPM is moving. If I start from 1st transition or 2nd the car works properly. After 3rd I can go to overdrive normally.
I connected to the car computer but no errors and nothing wrong with gear oil??
now after a day i just tried to move the car from one place to another around 2 miles using manual transmission, after i stopped the car stopped going forward at all, and now only the reverse work.
The turned out to be an indication that the transmission is going bad, I bought a used one, the cost was around $700