The last couple days the truck is noticably louder. Idleing ,part/full throttle, it doesn't matter. It has a lot more injector "rattle". It sounds very similar to when the pilot injection shuts off. I had 2 other people in the truck and they noticed it without me saying anything. I have access to a tech 2. What should I look for? Truck only has 8K miles on it. Checked oil level and it was fine, didn't smell like fuel. Any ideas? Truck otherwise runs fine.

I have noticed that if I purchase fuel from a different place my engine will sound different. I am thinking different fuels will make the engine sound different.