Hello Friends, my car has been knocking over the last 1 week while lowering gear. By the way, my car is 2004 307 1.6 Tecnoplus Automatic. There has been a low level of oil leakage for about 3 months. It gets enough traces on the ground. I add about 1l of oil every month. A question got stuck in my mind after this knock happened. Could it be from the gearbox oil? Does transmission oil decrease and cause hard knock in gear? I also searched for where to add oil to the gearbox, but I could not find it. If you say why don't you go to the master. I don't have financial means, I can't go for at least a few months. How do I control the transmission oil, how do I add it? I am waiting for an answer if there are bor friends with knowledge. Also, when I open the hood, there is a pet bottle-shaped black piece just to the right of the engine.