Hi everyone,This is my first post. I have been running my 07 S3 8P for 7 months and it has developed a misfire (Cylinder 2 according to error code). So I'm going to replace the plugs and coil packs because they're cheap and quick to do. However, whilst looking at the engine I noticed that the radiator was loose! Upon closer inspection the radiator bolts at the top were missing and the lower passenger side one was loose. So my questions are:Is this likely to have caused any other problems?What type of bolt do I need? I assume any metric thread bolt will do the job? It looks like a M5 thread?Also lot's of black sludge in the oil filler cap, only done 4,000 miles since last oil change...?I'm beginning to think the used car 'dealer' I got it off cut a few corners...Any help greatly appreciated!Will