Valvoline Premium Blue RESTORE. If you truly want to clean your engine from sludge - buy that oil. But not regular Valvoline Premium Blue. It HAS to be the Restore one. Around $75 per gallon, but it will clean your engine up in 1 OCI. Just give it full 5000 miles and top off with same Valvoline Restore oil as needed. No other oil or additive will clean as fast or as good as Valvoline Restore oil. The only thing that will get your engine cleaner than this oil is a rebuild. So either waste money on many OCIs and additives, or invest in ONE OCI with Valvoline Premium Blue Restore and see results after 5000 miles. Maybe even post them for us as well. Just change the oil filter every 1000-2000 miles as it will get filled up with trash very quick.