compression test

Hello! So I have made this post last year. Then I did a compression test. It turns out that piston 4 is very bad. Here are the results the service gave me: 1 - 13.4 Bar 2 - 11.4 Bar 3 - 12.0 Bar 4 - 7.2 Bar I do not know how much it will cost to change piston rings but it is easier for me...