I used that 5-min flush in an old motor once and never had a problem. I would only do it once though.
Some REALLY REALLY good stuff if you can find it is J-B(Justice Bros.) oil treatment.
THIS STUFF WORKS!! It kicks the snot out of MMO. You don't replace anything with it, you add it to your regular oil. The shop that recommended it to me swears by it.
They put some in a guys Suburban that had a real bad knock in it. They said they wouldn't have trusted this thing out of the parking lot it was knocking so bad. The guy just didn't want to spend the money on a new engine. They said the guy came back later and said it quit knocking and smoking after about 2 or 3 miles down the road. That was three or four months ago and he's still driving it around.
It has some kind of metal conditioner in it that bonds to the metal sufaces. I put it in my engine and highly recommend it. Lucas Oil dosen't hold a candle to this stuff. You can only get it from independent shops and dealers. They don't distribute it through chain stores.