Ultrasonic cleaning involves the breakdown of a reel and immersion into ultrasonic cleaner. An ultrasonic cleaning is superior to a regular scrub and brush cleaning. The ultrasonic cleaners cleans the oil, grease and debris to give the reel a new reel cleaning. It gets into all the nooks and crannies difficult to get to with a brush. Bearings have a complete oil removal. Excessive oil is one of the leading causes of a poorly casting reel. Many reels brand new out the box have too much grease and oil on them. Reel companies put extra oil and grease on their reels because they don’t know how the reel will be cared for. This typically hurts the performance of your reel. The grease and oil ends up getting into reel parts and thus hurting the performance of your reel. Personally I break down and clean any brand new reel just to clean off the excessive grease and oil.