Hello Scotty, and thank you for what you do! I recently bought a used 2014 ram 2500 with a Cummins turbo-diesel engine (62k miles). Everything seemed to be in great shape, until recently I have been hearing a low-pitched knocking sound between 500-1000 rpms. There are no check engine lights, and the truck runs fine. I do not hear the sound while in park, or at higher rpm’s. I have only put 3,000 miles on this truck. I don’t know when the last oil change was done, but I have heard that dirty oil can cause that in these trucks. What would you advise that I do?