Haven't changed my transmission fluid in 100k miles... Did I mess up?

I didn’t realize it was something I should do. Got my Kia Optima brand new in 2018 and now I’m at 104k miles. Is it too late to change the fluid? Should I worry?

Just get a fluid swap, not a full flush. That should help and it’s easier on the car.

RichardMiller said:
Just get a fluid swap, not a full flush. That should help and it’s easier on the car.

Exactly, just a swap is all you need.

My Kia Soul manual says every 60k for fluid change, but I waited until 120k and now I’m at 183k with no issues. Go for it, you’re probably okay.

I have a 2018 Kia Forte. Did my fluid at 103k, and now I’m at 190k with no issues. Just make sure you use the exact Kia transmission fluid and not a ‘universal’ kind—those don’t work as well.

Miles said:
I have a 2018 Kia Forte. Did my fluid at 103k, and now I’m at 190k with no issues. Just make sure you use the exact Kia transmission fluid and not a ‘universal’ kind—those don’t work as well.

Booked an appointment with the dealership for the 22nd to get it done.

@LebronJames
Good call. That’s what I did too. Cost me about $225, but at least I know they used the right fluid.

Nah, you’re not screwed. I know someone who went 170k without a change and the car still ran fine. Just do a drain and refill, no need for a flush.

My dad’s a mechanic and he always told me not to mess with the transmission fluid on modern cars. I’ve got two vehicles with over 140k and 190k each, and no issues so far.

I have a 2023 Kia Forte GT and my manual says I don’t need to change the fluid until 100k or 120k. Check your manual to be sure.

petrabrinkman said:
I have a 2023 Kia Forte GT and my manual says I don’t need to change the fluid until 100k or 120k. Check your manual to be sure.

Sometimes the manuals set long intervals for marketing, like ‘no maintenance needed for 100k.’ But a change every 50k miles or so can really help keep it running smoothly.

@Luchivya
I’d rather trust the guys who built the car. They give a 100k warranty, so they’ve done their homework. Sticking with the manual is safer.

marthakrausen said:
@Luchivya
I’d rather trust the guys who built the car. They give a 100k warranty, so they’ve done their homework. Sticking with the manual is safer.

True, but the manual suggests a 60k-75k change under ‘severe’ conditions. City driving with lots of stops counts as severe, so most people could benefit from changing it sooner.

marthakrausen said:
@Luchivya
I’d rather trust the guys who built the car. They give a 100k warranty, so they’ve done their homework. Sticking with the manual is safer.

Manuals only provide minimum guidelines. If you can, aim to do a bit better. Some cars claim ‘lifetime fluid,’ but it’s usually worth changing.

petrabrinkman said:
I have a 2023 Kia Forte GT and my manual says I don’t need to change the fluid until 100k or 120k. Check your manual to be sure.

Even if the manual says 100k, I’d go for 80k for the first change and then every 30k after that. Just to be safe.

I’d do a full flush around 100k, but if you’re over 120k, maybe just leave it alone or do a drain and refill. If you’ve already got issues, a flush won’t help much.

nesh said:
I’d do a full flush around 100k, but if you’re over 120k, maybe just leave it alone or do a drain and refill. If you’ve already got issues, a flush won’t help much.

Haven’t had big issues yet, just:

  1. Burns 1 qt oil a month, pretty normal for a Kia
  2. Sometimes jumps after a cold start
  3. Had a weird noise two days ago on startup but it’s gone now. Added some oil, and it’s fine

Got a dealer appointment for that, plugs, and coolant. Still drives great. Thanks a lot ,

Man, every time you went in for service, they probably suggested a fluid change, right? Did you get it done yet? If you didn’t, it could be worth checking for any metal shavings in there.

Cole said:
Man, every time you went in for service, they probably suggested a fluid change, right? Did you get it done yet? If you didn’t, it could be worth checking for any metal shavings in there.

Actually, no one ever mentioned it, and I go to the same place every time. Not sure if they just missed it or what.

@LebronJames
Don’t listen to that guy—he has no clue where you get your car serviced, lol. But yeah, the fluid recommendation is usually every 60k miles.