if youve got a 1.6hdi and use ANYTHING OTHER than low saps fully synthetic oil your heading for trouble with your turbo. google 1.6 hdi turbo trouble. also remaping a 1.6 for extra bhp isnt a good idea as the turbo wont take it. the 1.6 is a good economical engine when serviced correctly and in a small car but is a c5 it has a lot of weight to pull around so the turbo does all the work. Also a good flush every oil change and once every 2 year pull the sump and turbo oil feed pipe off and give it a good clean out. youd be a fool to ignore john,s or mike,s advice regarding the oil