Guys, I bought my fg mk2 turbo new it now has 35,xxxkm on it. It's first oil change was at 7500km using penrite 10 tenths, forgot the grade 10-40 or 50. The car seemed to feel a lot more responsive but on idle it was shakey used to sh*t me. I used this oil (full syn) upto 22,500km with 2 changes. From then I had Castrol edge sport 10-60 and it ideled so smooth it was great. But under acceration it felt sluggish as if the motor was strained. 5000km after that I'm now running nulon full syn 10-40 and it feels very responsive again. But now idles roughly from time to time.. So not sure I'm happy with the nulon. What should I run? Do my problems sound oil related? Many different mechanics and ford said they are all fine choices and not related but I'm sure they are. Should I give it a flush and start fresh with a new oil?