Hello! Could I get some help identifying this noise please? When the engine is cold it is completely quiet, as it warms up though it starts to make this noise. I originally thought that it was the rockers/lifters but it is not. I opened up both valve covers and everything was tight and good. I still replaced all the rockers/lifters just to be safe. The noise is still there and didn't get any better or worse. The inside of the engine is SUPER clean. Oil pressure is perfect and NO codes. According to Carfax it has had 20+ oil changes over the past 6 years. I'm afraid that it is a rod bearing but not sure. The noise is definitely on the bottom end of the engine. I tried a Penzoil 5w-30 synthetic to see if that would make any difference but it did not. The Jeep has 86,000 miles. Please let me know what you think. Thank you for any input that you can provide.