I've the same very problem. Every time after service car with Shell Helix oil, car engine gets lauder and sluggish. I can confirm there was a change when EON service center used Petronas Syntium oil when i serviced. (that was at my home town). I recently serviced my car again at Proton Edar service center (the usual place i service my car and they use Shell Helix) and i can tell you the different was obvious. I feel car was much more smoother when used Syntium.

This post has been edited by jaya7: Mar 31 2010, 06:00 PM