I bought a 2014 Toyota RAV4 in good condition having done 109,500 km. In the first week, when doing 40-60 km/h I heard sounds from the transmission. I went to a mechanic and he changed the transmission oil, which is less thick. The noise is still there. I need your advice.
You have a CVT transmission. Take it to a Toyota dealer, or an automatic transmission specialist and have them assess the transmission. It could be that it needs to be serviced.