Oil query on greade ? garage says I'm using the wrong stuff

Pete · 2011-09-13T19:25:30+00:00

mk4 golf 1.6 8v 1999 autoHello all,Basically the car went in for a service today and I have 5 litre of car lube 10/14 semi synthetic oil which has been used for the last 3 years in it. Its first service was done at a vw specialist and they used this infact it was quantum oil but same spec.New local garage I'm now using said I've been using the wrong stuff and reckon it should be 5/30 fully synthetic ?Can anyone confirm which grade goes in ?I asked them to hold off on the oil change while I dug in to it, they weren't best pleased to be questioned but hey ho..