Points to note:-1)If the sycros are shot the cocktail wont help,you need it to prevent the problem,it wont fix it if you already have a syncro prob. 2)If the syncrs were shot before the shifter was fitter they will be shot after ! 3)No a correctly installed shifter should not cause any grind ...4)The latestest boxes do have revised syncrs & shifter forks which help the 2nd gear problem...most of us dont have them...the internals are 2000+ Mondeo type...
