As of 10th January 2018, they are now turning into 8 cars only on Cherkizovo depot. The oldest depot on Moscow Metro is Severnoe depot opened on 26th April 1935 which sadly doesn't fit 8 cars, only 7 cars.
It's the oldest line opened on 15th May 1935 with 13 stations from Sokol'niki to Kul'tury Park and to Smolenskaya which is now turned into Line 4 like separate line from Kominterna Street (now Alexandrovsky Garden) to Smolenskaya.
![](https://s2.save4k.ru/pic/qR3wIysD4YU/maxresdefault.jpg)