I have a 2.0 SRi with X20XEV engine, and like all Astra's it doesn't like it after sitting in traffic, and thanks to heat soak it loses some of its 'go' for 1/2 mile or so, until the temp comes back down.
1) Is there anything you can do to stop this becoming such a factor?
2) What is the 'normal' operating temperature for the engine? Mine hovers between 85-90, but goes up to 94/95 if stuck in heavy traffic in warm weather. (best performance appears to be when engine is 85-87).
3) In 18 months of driving I have never heard the fan kick in - is it faulty or does it need to be much hotter for that? (never seen temp gauge go over 95)
4) Would a cool running thermostat make much of a difference? (What temp is 'cool'?)