If you want to ensure that the oil galleries are clean, then try using engine oil that's designed for diesel trucks.
This is a high detergent oil and it will steadily dissolve any sludge buildup in your engine. Be prepared to do more frequent oil changes and always use a new filter. The original 1200 filter is still available and it is bigger so it will last longer. Change the oil when it gets black, or at normal service intervals, whichever comes first.