Thanks Ozawa for your reply. I do actually see temperatures below -5, only a few days though. But the owner before me had the car in the same area. I know that it will still start at temperatures below -5F, but is it possible to damage anything like an oil pump for example? Also i don't really want to switch to synthetic. The engine has only seen dino oil in 12 years, and switching to synthetic doesn't seem the right thing to do.
What about the knocking sound, any comments?