Gearbox oil change Help!!!!

[S3 Dave]

Cars in for a service 2mrw and am thinking to get them to change gearbox oil little bit notchy!! Silktran syn 5 looks the bis but where can i buy it today???????? I'm in Redditch west mids Anyone help??? Or is there another oil Easily available ie Halfords etc!?!?!?

 

[jonS3]

I only ever get it from opie oils mail ordered, never seen it for sale anywhere else