A long time ago I tried BG MOA. It is supposed to reduce the oxidation of oil and make oil last longer, and also help to keep an engine clean. I tried it maybe one or two times. Maybe a some amount added to known sludge monster engines would help.
I tried it in a car that I was using Mobil 1 oil in. Maybe I put too much in because it seemed to reduce the performance. If you use it, use only a small amount, especially in a small car engine.
BG products are very highly regarded by some people. The BG44K fuel system cleaner is extremely highly regarded-I have heard a lot of people talk about it. In fact, when I went to the new Saturn dealership in Pueblo, I saw BG products on the shelf, including some I had not heard of before. There was one called something like BG 'Quick Clean.' I don't know if that is an engine flush or some sort of oil additive.
I have also noticed BG44K at Honda and Toyota dealerships, and I know the local GM dealership has it. It has been my experience that you don't find stuff at new car dealerships unless there is a high probability that it works. You don't find buck and a quarter fuel injector cleaner at a good dealership.
I have tried BG44K fuel system cleaner and it is powerful stuff. The injectors are likely going to be clean for at least a while! It is also expensive. It might be a good idea to use it only once or twice a year and a few hundred miles before an oil change.