Since I've already asked you about the type of engine oil, I'll also ask what kind of petrol you use in your Crossfires?
I initially filled up with 95 petrol, because that's what the previous owner filled up with, and that's what the owner's manual recommends.
But then I read that it's better to fill up with 98 petrol for powerful engines in sports cars, and I'm currently using 98 petrol.