I have a 2005 G35 Sedan with 174,000 miles on it. The last few months I've noticed pinging noises that have been getting worse. The pinging noises is most noticeable between 1500-2000 rpm but can be heard at idle. I've also noticed that I have an oil leak that seems to leak more when the engine is running. I fear the worse in regards to the engine since it has so many miles on it but any suggestions as to the cause of the issue or tips on figuring out the issue is very much appreciated!