Hey all,
I have a 97 XJ with 220,000 miles. I bought it at 184,000. I first used the Farm & Ranch stores MAG1 10w-30 with Auto-RX through two clean & rinse cycles, changed the head gasket and resealed the bottom end, and then used Shell Rotella T5 10w-30 twice at short intervals. I wanted to cut open the filters and make sure no debris from the engine work. It was quiet the entire time. Then I switched to Amsoil synthetic. Immediately after the oil change, when idling it sounded like a Mercedes diesel after a warm start. It goes away at RPM. I used 4 quarts of HDD and 2 quarts of AME. I drove it about 13,000 miles and changed the oil this time using 3 quarts of HDD and 3 quarts of AME. The diesel noise is still there. Oil analysis shows better than when using mineral oil.
This is my second 4.0. I have another one in an 01 XJ with 340,000 that I've been using synthetics in for over 300,000 miles and have been using Amsoil for the last several years. In that one I've run mostly the thicker AMO 10w-30 or AME 15w-40. It sounds fine except for a lifter tick.
I am wondering why the sudden change in noise with going to synthetic. It literally went from quiet (not even lifter noise) to a diesel with the synthetic. No other work was done between the oil change. I am considering trying AME 15w-40 in this engine, or trying another round of Rotella T5 10w-30 or even the Rotella T6 5w-40 at the next oil change.
Any suggestions?
I've had Mercedes diesels for years and it really does sound like one at idle!
I have a 97 XJ with 220,000 miles. I bought it at 184,000. I first used the Farm & Ranch stores MAG1 10w-30 with Auto-RX through two clean & rinse cycles, changed the head gasket and resealed the bottom end, and then used Shell Rotella T5 10w-30 twice at short intervals. I wanted to cut open the filters and make sure no debris from the engine work. It was quiet the entire time. Then I switched to Amsoil synthetic. Immediately after the oil change, when idling it sounded like a Mercedes diesel after a warm start. It goes away at RPM. I used 4 quarts of HDD and 2 quarts of AME. I drove it about 13,000 miles and changed the oil this time using 3 quarts of HDD and 3 quarts of AME. The diesel noise is still there. Oil analysis shows better than when using mineral oil.
This is my second 4.0. I have another one in an 01 XJ with 340,000 that I've been using synthetics in for over 300,000 miles and have been using Amsoil for the last several years. In that one I've run mostly the thicker AMO 10w-30 or AME 15w-40. It sounds fine except for a lifter tick.
I am wondering why the sudden change in noise with going to synthetic. It literally went from quiet (not even lifter noise) to a diesel with the synthetic. No other work was done between the oil change. I am considering trying AME 15w-40 in this engine, or trying another round of Rotella T5 10w-30 or even the Rotella T6 5w-40 at the next oil change.
Any suggestions?
I've had Mercedes diesels for years and it really does sound like one at idle!