I ended up leaving my rover outside overnight, with temps getting well below freezing. I got in it this morning and started it up, but noticed some clacking noises coming from the engine. My other car does this for about 1/2 of a second and then the noise goes away. The rover kept the noise going for a good 30 seconds until it was some what "quelled". However, it still made ticking noises at idle. After about 30 minutes of driving, the ticking noises stopped and everything started sounding normal. I am using 10w 40 oil, I would not think that this would not cause an issue, but maybe. Could it be the knock sensor malfunctioning or bad timing? The spark plugs are pretty dirty (I will be replacing them here shortly) I do not know where to start, and would appreciate any input. Thanks in advance!