Automatic transmission, won't shift gears

I put more oil in my car yesterday (I was low/almost out) and today when I got on the freeway, I car wouldn’t shift in the highest gear (Highest? Or lowest? I dunno which is which). It shifted a couple of times but was struggling to shift on the last gear. I could feel the car trying to shift and the RPMs go up and down but it wouldn’t shift, and a lot of white smoke came out of the exhaust (I assumed it was the excess gunk burning off or oil I had spilled in the engine compartment). I don’t get any weird sounds or rough idling or anything when I drive, it just won’t shift. About halfway through my drive to work (it’s a short drive, only about 10 miles) my check engine light came on too and I don’t have access to an OBD reader. I’m probably going to have to take my car to the mechanic, but how long can I put it off? I can do it in the morning more than likely but I just had my days off and I don’t know that they’d be able to get to it before I had work, especially since it’s a Sunday.

Are you sure that you added oil to the engine, rather than putting it into the transmission?
Did you bother to check the trans fluid level, either before or after adding that motor oil?

Whenever you are able to get this car to the mechanic’s shop, I urge you to have it towed and to NOT start the engine.

Mark Something with a Car Something
Make, Model, Model-Year, approximate number of miles?

Is all recommended maintenance up to date? :blush:

I did not check the transmission fluid. To be honest, I’m not 100% sure where it is in my engine, most of the engine block is covered. The oil however definitely went in the receptacle for motor oil, has the little oil can icon on the cap and everything

If your handle is MarkSomething, then we must assume you vehicle is Something!


Sorry I thought it automatically put in the info for my car, and that’s why it’s in the profile. It’s a 2005 Hyundai Elantra. I’ve had this car for about a year and never had problems with it changing gears until after I put oil in it

So it looks like I’m low on ATF, if I fill it up, how long should it take for the check engine light to go off, assuming that’s the issue? Do I let the car idle for a bit or should I drive around the parking lot?
Also sorry for being a pain, what type of ATF oil should I use? My only option right now really is Ace Hardware

ATF is not ordinarily consumed. Usually if you are low then you have a leak. It needs to be fixed.

I would only use the fluid required by the manufacturer and it’s not likely you’d get that at ACE hardware. You could go from a relatively minor problem to a major problem by using some kind of “universal” or “close enough” fluid.

Do it right. Walk, take the bus, hitch-hike or whatever, until you get a handle this problem.


Yeah Ace didn’t have any that met SP-III requirements, let alone the brands recommend by Hyundai

Are you positive that smoke came out of the exhaust and not off the exhaust?

Transmission fluid dripping/leaking onto a hot exhaust system will put out some smoke!

You do know that you check your tranny fluid with the engine running after you drive it about 7 to 10 miles, right?

If the town you live in is big enough to have an Ace Hardware you should also have an AutoZone, O’Riellys or some kind of parts store.

Yeah the issue is I work the night shift and I don’t get off until midnight. Ace was the only store accessible on my lunch break. And it may well have been that it was leaking on to the exhaust rather than smoking out of it, it did look pretty dispersed

There is a major leak? I didn’t see that in the original post.

I think you may need to make funeral arrangements for this car. There is a possibility that the leak is inexpensive to repair but something like a failed front pump seal combined with driving with insufficient fluid may cost more to repair then you are willing to spend on an old Hyundai.

If you try to drive this car home without fluid the transmission will likely be damaged.

How are you determining you are low on transmission fluid?

I’m sure the steps for checking are in your owner’s manual, but they’re likely something like:

  1. have the engine running and up to operating temperature
  2. the transmission in neutral,
  3. the car on level ground.

If the oil level is between the high and low marks on the dipstick, or even just slightly below the low mark, then it’s likely not the cause of your trans not shifting.

Can you reply with the details for how you checked the fluid and exactly where the level is?

The level was just below the Hot line. I checked it probably about 20 minutes after driving to work, let it idle for about 10 minutes, then cycled through gears and put it back in park. I have a mobile mechanic coning to look at it tomorrow because I don’t wanna drive it.

Hi Mark:
Thanks for that update.
If the level was just below the Hot line, then it’s not really low. Your problem of it not shifting is not due to a lack of fluid.

Given your symptoms there’s a good chance that the transmission is just worn out and needs to be rebuilt or replaced. Automatics have clutches that wear out just like manuals, just that there are more of them w/ automatics. Before doing that, usually a transmission shop would recommend a proper service to see if that helped. If it did seem to help, but not completely fix the symptoms, they’d probably suggest to repeat the service procedure once or twice more over the course of a month or so.

I’ll throw in something else! Perhaps there’s not necessarily a transmission problem.


The “check engine” light could be warning of another problem, perhaps engine related, that is keeping the transmission from shifting properly by placing the car’s computer into “limp mode” (program). That is to help protect it from hurting itself until the problem is corrected.