Hello there,
One of the cars I own is my beloved 2012 Hyundai Accent that has served me well for the last 9 years and 100k miles with the 4 speed automatic.
At about 50k miles the transmission control unit was replaced under warranty by the dealer.
since then at about 95k miles I started to feel the transmission would very slightly hesitate before shifting gears.
So since the oil started to darken I decided to ask my mechanic to change the oil - afterwards the transmission developed shifts that feel like they're pulling you back in your seat, and a vibration in 3rd and Reverse, with very poor and slow creep.
When I inspected the automatic fluid situation I've discovered it's clean but severely (pretty much 2x the correct amount) overfilled,
could overfilled AFT levels cause vibrations and rough shifting? or are we talking about permanent transmission damage?
IF that's permanent damage,
Should I bother draining the transmission oil? or putting in a junkyard transmission with a warranty (about 850$)? or should I start looking for a better built used 15k-20k car like a Renualt GrandTour 1.5 dci or a Mazda2 1.5 GDi?
If it was overfilled that much, it's time to start looking for a new car.
You can cause permanent damage that is beyond repair by driving a vehicle with an overfilled transmission. What happens is you create more pressure as things heat up, which causes more pressure on all your seals. In addition, when severely overfilled like you described, the gears themselves can become submerged in fluid and cause foaming to occur as temperatures rise. With air not being able to cool the fluid, you basically have a superheated, high friction environment that nothing good is going to come out of.
I wouldn't chance $1000 on a junkyard transmission. It could be bad too and you would be out your money.
I would suggest looking for a replacement vehicle in your situation.
