link doesnt work for me mate but if its diesel fuel system/injector cleaner then it goes in your fuel tank.

if its not been serviced in 5 fucking years (how many miles has it done) then get it serviced!!! including fuel filter and get the brake fluid changed!!!! its amazing what a service will do. then with the fuel system cleaner in give it a good booting!! and put it in for 2 or 3 tanks will help. oh and use shell diesel not shitty asda or tesco etc.