Clicking noise after oil change.

Ever since I changed my oil there is a clicking noise coming from the engine when around 1500RPM. If the RPMs increase the noise stops. I used 5.5 quarts of fully synthetic 5w-30 just as the manual says. I bought the truck with 29000 miles on it and it is at 34000 now. Any ideas on what this is?

 

It's the spark knock issue and there is a tsb for it as well as a large thread. I could be wrong but I think changing to synthetic brings out the issue some how. The reason I say this is I didn't notice it until after the dealer changed my oil, I assume they used synthetic. Several other forum members reported hearing this after an oil change too.

The noise was so loud I thought a tech left a tool under the hood until I realized it was knocking or pinging. The tsb fixed it for a while but I'm hearing it more and more lately.