Go to the GT Auto shop... It should be the engine picture 3rd from the right side... Says Overhaul Engine.. Just make sure you got enough cash to overhaul it.. Some cars are really expensive...
He said how can you tell, not how do you do.
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.