Direction creaking

[Olive]

Hi guys, maybe somebody already met my trouble.

When the car is cold, no trouble, but after 1 hour of driving, especially with high temperature, the direction become more hard, not "smooth" anymore and on low speed and small virage all the front axle make a big creaking.
This noise stops when I spray some oil on all the silent blocks behind front wheels (direction,stabilizing bar, ...) and come back latter after 30 to 50 minutes.

I first thought the problem came from one of the silent blocks but a friend told me about steering wheel fluid. I checked and the level was quite low, that is right :



I will change the ATF and add more but I really do not think that the problem come from it.

Do you have an idea about the root cause ?

Thanks