New to me 2001 Dakota sport 2dr club cab. 4.7L 92000 no rust. Dealer had a fresh oil change when I got it. There was a slight growl at cold start up but went away quickly. Since then I have come to know is the hated 4.7 by some. Sludge and all that stuff. I decided to run some Marvel Mystery Oil for a light flush and do a oil change at 1000. Approaching 1000miles sucked out a quart of oil and added the MMO.At first no change still just the slight growl at cold start. After 50miles the growl is now a tic at cold start up. Still goes away after a min or two then runs quiet.I couldn’t get the oil changed for a day after it started ticking at cold start up so that was about another 50 miles. I got the oil changed today. Conventional 5w30 and a new filter. Started it up and quiet. No growl or ticking. Im going to change at another 1000miles. No MMO this time. So did the MMO work? I don’t know. Will I ever put MMO in my oil again? Not a chance in hell.

 

Here is a pix of the mopar oil filter. The guys over at bobs are telling me the MMO worked and maybe do another treatment. I don’t know Ill have a few miles to think about it.

 

I believe what you are hearing is the sludge flushed out and no longer being a sound dampener to the lifter tick...