Elantra shifting down hard! forcing to almost stop! maybe tranny issue?

Ok I am the original owner of my 2003 Hyundai Elantra. Just recently at 55k miles I started having problems (O2 sensor went out last month). But this morning on my way to school it slammed/clunked into almost a full stop! It is an A/T. I am wondering why it does this coming out of 15 MPH??? HELP! has N E one experienced this?:banghead: N E suggestions?

Hey, the secret to making engines and transmissions last is to use synthetic fluids.....the best is Amsoil (www.amsoil.com). Also, we had a car that was shifting hard and we put in a bottle of "Transmedic" additive.....that solved our problem. Hope this helps!

NOOOOOO !!! NEVER EVER put somthing else than Hyundai oil in a AT Hyundai transmission. AT Hyundai transmission = SP III oil ONLY!!!! it's available at Hyundai dealer, if you put something else in it'll die after a few thousand miles AND Hyundai will not cover it under warranty (seen it happened more than one time!).

gneissgurl, is the the car still under warranty?? if so, you should go back to the dealer for them to fix it.

Also could you give more details :

- what do you mean by "shifting down hard", the tranny actually down shifted into first gear?
- is there any grinding sounds?
- can you shift it into other gears? (other then Drive)
- is the car running ok in neutral?

Hey Gneissgurl,

I have used synthetic transmission fluid in my Elantra for 70,000 miles...thats right 70,000 miles with no problems whatsoever. As soon as I god rid of the original fluid, I noticed smoother shifting not to mention the 100,000 mile change interval the synthetic fluid offers. The only problem it causes is not making money for dealerships that charge outrageous prices for a subpar product! Haha

dmiller, do as you want but you have to know that non SP III fluid in a Hyundai transmission will eventually kill it, don't beleive me it's fine, but you'll have to convince the 2 tranny I've changed on my car because I used something elase than Hyundai's oil.

And you also have to know that if it dies when the car is still under warranty Hyundai will ask for service records AND will void the warranty if something else than SP III was used, again you'll have to prove me wrong on the few cases I've witnessed AND the fact that Hyundai have a TSB about it also.

If you want to put something else than SP III (which is synthetic oil BTW) and take the risk to bust a 2000$ part, then go ahead, I know that I will never do that again. Aftermarket oil and Hyundai's oil are often the same price.

BTW dealer's price are not that outreagous, I've seen lot's of small garage charge more for an AT oil change than my dealer and lots of parts are actually bit cheaper then aftermarket ones.

I will probably end up ageeing with you after I get the bad news on my 00 Elantra trans. Changed the oil with Amalie Universal Synthetic at 95000, and now at 110000 getting a kind of groaning sound when starting in 1st that goes away once speed over 20mph or so is reached. Sounds like a rebuild coming on. All this because I didn't want to pay the price for Diamond SP3 (the Amalie was cheaper by less tha a buck a quart). Learning the hard way here.

Thanks Joseph, I'll just point out that I am not working for Hyundai, so I'm not saying that over money interest and I've experienced the SPIII only problem by myself and others that I know.

I've seen Hyundai's tranmissions fail after a few thousand miles after a flush with "universal" synthetic oil. (mines lasted about 25k miles, not enough saving 20$ on a flush).