How much power does your Bob really need? I would just keep changing the oil until it gets down to something really sad, like 1200HP. Even then it might be a waste. I overhauled my engine when the hp after oil change got down under 1500. I thought about it afterwords and realized Bob was doing fine with the 1495HP...waste of 500k imo. Right now, Bob's X2010 is down to something like 1452 and I have no intention of rebuilding any time soon. He still crushes the competition.