There are additives that will break up the sludge, however I do not suggest using them. Think of sludge like chlestorol in your blood. It gets in there, and circulates around and usually finds a place to build up. Over the years the build up, if in the wrong spot can cause a blockage and then stroke. Now, on the other hand, if we go breaking up the sludge and have it start flowing thru the system again, we run the chance of it collecting in the wrong spot and causing a stroke.
So, Dr. Mike is going to tell you to do your oil changes and try to avoid new build up of sludge. The engine is running good now, and as long as it doesnt build up more, then you should be alrite. It did make sense that if there are some hot spots burning the oil, it may make sludge reguardless of what you do. But are you going to go thru life worrying about the what might happens? Do what you are supposed to do, and hopefully your car will not have problems. If it is going to make you crazy with worry, then sell the car while it is working good.