I'm new here. This past week or two I have noticed that my car is having issues switching gears first thing in the morning. (sorry if i'm not explaining things correctly, not a car person). I live in the Northeast. Every morning I start my car to let it warm up (5-10 minutes). This past morning, I warmed it up again. I'm trying to accelerate but at 20mph, it doesn't want to accelerate any more or change gears. I slowed down and then tried again. This time it shifted hard to accelerate beyond 20mph and then my check engine light came on. After that hard shift into gear, everything seemed to be okay. No more issues after it "warmed up"

I've been reading on here about transmissions problems and truthfully can't remember if or when I've flushed or drained (partly) the tranny fluid. My car has 154K miles. I'm the only owner. No big issues until this.

I just made an appointment with a car place near my work. I want to make sure i'm asking the right questions before I let them walk all over me and try to upsale me.

 

I've also heard that I could add a "tranmission helper" or "tranny doctor" to help with this issue, but I don't know if I should do that. IE drain a quart of transmission fluid and add the tranny doctor? If this is a good low cost solution what should I use for a 2003 Elantra GLS??

 

Don't use the "tranny doctor". You have that old nasty trans fluid in there. The first thing to do is get a trans flush from the dealer. It has to be Hyundai spec fluid, so best to go with the dealer. You need to check your error codes too. You can do this for free at Autozone.