How do I remove oil sludge from engine?

How much is too much oil? Overfilling the oil is not what forms sludge. There are a lot of really good additives in today's oil so sludge buildup shouldn't be a problem if the oil is changed on schedule. If the buildup is really bad, an old trick is to add about a quarter of a quart of automatic transmission fluid to the oil, drive the car for a day or two, then change the oil and filter.