[Bob.W]

Hi Folks,

I'd been holding off replacing the DCT fluid in my 2017 MY18 i30 but thought I'd give it a whirl yesterday.  Ended up being super simple (though I cocked up a bit myself - posting so others don't do the same).

Seems nearly all Hyundai & Kia DCTs are very similar - so feel free to apply to other models.
SUFFICE TO SAY DO NOT GET UNDER YOUR CAR USING ONLY A JACK, HAVE PROPER STANDS OR RAMPS!
1. Remove the under motor plastic guard (has around 10 hex head screws and a dozen or so plastic press clips)
2. BEFORE you drain the fluid (& obviously have the required 1.9-2L of replacement fluid I used Penrite Progear 70W-75) make sure you can loosen the plug/hole you intend to put the new fluid in!!!!
3. The official inlet hole to use is a bugger to access, at the rear of the DCT and up with very tight access - I strongly recommend you DO NOT use this one as it's too hard to access both for undoing and also adding the new fluid.
4. I instead used the one at the front of the DCT, that has an 8mm hex head, generally it's black in colour. Make sure you can loosen this - it's on quite tightly!
5. If you can loosen it, great then proceed - dump your old fluid into a container (dispose of properly , most local councils or auto stores will take for free).
6. I allowed mine to drain for a good while, wipe down replace drainage plug. Can reuse the crush washer or replace if you want.
7. I considered several ways to refill deciding to use some poly piping I had ~8mm internal diameter, with a small funnel on one end of it - then the other end going into the inlet hole at the front of the DCT, just run up through the engine bay (you need 40cm+ of it) - gravity then will feed the fluid down into the hole.
8. BEFORE YOU START mark on your container the level you need to go down so you only put in 1.9-2L - and start pouring, can do a one man job or two - the hose will go in to the right side of the hole and fill it fine.
9. Stop when you've added the proper amound of fluid, do NOT add extra (can cause issues)
10. Wipe down any spills, replace the under engine guard and give a short test drive.

Is super simple - the trick with using the front hole is it is HIGHER than the rear hole so when the proper level of fluid is in the DCT you will NOT get any coming out the hole, but just put the proper amount in (1.9-2L) and you'll be fine.

Cheers,

Bob

[TerryT]

Bob, nice write-up.    Your comment to "...make sure you can loosen the plug/hole you intend to put the new fluid in!!" is, imo, the single best piece of advice in that post!   Don't ask me how I know. 
 

[Bob.W]

Bob, nice write-up.    Your comment to "...make sure you can loosen the plug/hole you intend to put the new fluid in!!" is, imo, the single best piece of advice in that post!   Don't ask me how I know. 

Hi Terry,

You're too kind =- that was a very minimalist rush job description.  This thread is one with some pix for folks that might assist:
How to change Elantra N-line DCT transmission fluid | Guide | 7 speed dry DCT | Hyundai Forums

Yes, thankfully I've not found out the 'hard way' on that tip but I thought it was good advice someone else gave so popped in. I must say even the hex head inlet at the easy to access front is very tightly done up - took a lot of effort to undo it, thought my hex head was going to break!  Hate to have to use that tricky rear access point.

I changed at ~96,xxxkms, the fluid that came out was significantly darker than the new stuff - think maple syrup type colour.  No metallic fragments etc in it - I did drive a fair bit before hand and dumped it when hot.

As we're admitting errors, I stuffed up in the early part of this change - I'd intended to do this change years ago but got scared off it (which I should not have as it's very simple) - I'd forgotten how much fluid had to go in but new I had ample. My mistake was assuming the front inlet was at the same level as the rear one, which it was not.  Stupidly I initially put the entire 2.5L in the front inlet, being shocked it'd not flowed out yet, in a brain fart I added around 500ml of the old fluid fearing it was too low.  This was incredibly daft as I then reaslised my mistake - and I weighted up just dumping ~1L of the fluid and making do with the sullied new & old mix in it or dumping all out and doing over.

I went with the latter, drove into town after taking out ~1L of fluid, luckily repco had the fluid on special grabbed another 2.5L, dumped the new+old mix in it - treating it as an expensive 'flush' and popped the 2L of new stuff in.

[TerryT]

Bob, when I read your "...I then realised my mistake...grabbed another 2.5L, dumped the new+old mix...and popped 2L of new stuff in" I felt a spiritual connection, brother.      Two types of amateur/home mechanics...those who have done this (or similar) and those who have yet to. 

The ever-vigilant fussy Virgo in me just would not let me run with a sullied mix.