I have been told that sludge buildup in this
No way. Unless you sit in city traffic for 8 hours a day, I don't think you can trash an engine that fast. Especially if you have changed your oil. First thing you do, Is get a can of Marvel mystery oil, when your oil is one qt low, dump this in. Or do it next time you change it, make it the fifth qt. Save the filter, mark on the filter "before", Then get some fuel injection cleaner, and fill it up with high test. Now were going down the turnpike!!! Run that thing, fast, step on it, burn that stuff out of there, pass a few cars. Next time you change the oil, get the old filter, mark the new one,(after), take them to somebody who will cut it apart for you. Look at the paper elements and see the difference. You probably won't believe it! This operation may take a month, but try it. Or you can go back to the dealer and pay him $4,000 to do what you just did for $10. One more thing, if it doesn't run better, take a qt of water, and pour it down the intake with the engine running and your hand on the throttle, rev that stuff through there, it will steam clean the inside of your engine. You only have to do this if you think the dealer is right, if your car is running ok, somebody is pulling your leg. But this won't hurt. And it will clean out your engine.