I have been told that it common to use a litre between servicing, though it certainly shouldnt be juddering. My old MK4 did use up to that between services but seemed saound apart from that. Check out the breathers as well as they seem to get clogged up duuring the winter. I was told by my maindealer that aircon units are supposed to make noise, 6 months later the bearings failed and was all repaired under warrenty.
If in doubt get it checked independently.
