Hi guys,
I have Hyundai i30 2011 Hatchback with engine size 1.6. Today I checked the transaxle fluid and it was brown and a little bit dark. And I guess it's time to change. But I got some questions like:
1- If you have this type of car should you change or flush the transaxle fluid in the car. A lot of people say if you flush the fluid in the car it may cause problems. So what is recommended?
2- What is the best transaxle fluid? In my owners manual it says under the classification sections you can have DIAMOND ATF SP-III, SK ATF SP-III. So which one is the best one to use? (price doesn't matter)
3- How much should you fill up? People say that you should put back as much fluid as you took out. But that doesn't make sense because what if there is not much fluid? or the owner before put not much fluid to save themselves money. In my owners manual under the volume section that that for diesel engines 6.6 / (5.81 lmp. qts.). Is that how much you should put?
Thank you any help would do 
There's going to be all sorts of opinions, but here's mine from an unqualified point of view. I've owned Mitsubishis as well which used SPIII which is a Mitsubishi specced fluid.
I've flushed 2 x F4A51 Mitsubishi boxes with no issue. And I have 2 x 1.6 CRDi I30 and I've flushed them out too, also no issue.
I have read of issues with really badly neglected boxes full of debris that may shift and get lodged in a flush But a 2011 box unless it's done an absurd amount of miles and been thrashed , you're probably safe.
There are professional flushing machines out there but I have little knowledge in that area.
For the DIY, which I am I found it fairly easy to do.
Draining from the pan you may get 2-3 litres at best out.
I have posted some imagery on a basic setup in another thread..
In a perfect world you could remove the pan, clean the magnets, replace the internal filter but you'll either need an aftermarket gasket or liquid sealant suitable for the pan which is how it's factory sealed. One of mine had the valve body replaced and they used a gasket, .. it leaks slowly.
I'd have to go look for it but this is how I did mine
Remove drain plug, drain what you can. refit it. Pour in the amount drained say 2.5 litres of clean fluid.
On the radiator as you face the vehicle are 2 hose connections, upper and lower. they connect to the internal oil cooler.
If you discoonect the hose from the upper pipe at the rad, then loosen the pipe at the radiator17mm I think) carefully rotate the pipe to the top of the engine bay to make things a little easier, then nip the flange nut up.
I used clear pvc tubing, I think 5/16 or 8mm, connected to that pipe, then into a bucket which i secured it too so it did not come out and spill every where.
Start the car and watch the old fluid being pumped out through the torque converter.
The moment pressure slows or air pockets appear, shut it down, refill again 2-3 litre, continue and repeat.
Once the fluid becomes clearer and nice red then it's safe to assume the flush is complete. If you continue until it aerates again, add 2 litres , Reconnect the hoses and piping as they were. On level ground start the car, run the selector through all ranges , then stop at Neutral (not Park).
Use the dipstack to check level. there is a cold and hot mark. Check it is at cold or just above. I found checking the fluid tricky cold after refilling, .
take it for a drive to get it at normal temps in the trans, then recheck the level(in N) should be at the Hot mark. Top up as needed. maybe do it in small amounts until it's right. I don't remember what th edifference is from cold to hot but maybe 250ml at a time.
I've used SPIII from Mitsubishi and also Penrite Multivehicle FS ( full syn) with no issues.
I found my local dealer useless and they did not sell non - commercial amounts .
Here at least I can get SPIII from Mitsubishi in 5L bottles and generally cheaper than the 4 L aftermarket fluid from local shops.
