I have Hyundai Accent 2004 Manual.
When it is cold at the startup and up to 10-20 miles I can change gears smoothly. But after that it starts getting hard and very difficult to change. If I pump clutch pedal 2-3 times i can change gears. When it in top gear 5 and on highway I drove 300 miles no problem
When I checked Clutch oil it was very very dirty. I am replacing / replenishment it from top, by emptying small container and putting new but no improvement.
Any Idea what is the problem.

 

You need to replace all the fluid, not just what is in the slave cylinder. And bleed the system. You probably have water and/or air in the lines.

 

I am not very tech how to replace or bleed oil
Thanks a lot

 

Then take it to a mechanic.

 

how many gallons it give but unfortunately problem stays