I run long OCIs in my '07 Sivic Si with Amsoil sig series 0w30 with lab proven great results. I recently used half a can of Amsoil Power Foam just to keep things clean at 100k miles. I fed it through the throttle body as instructed. I didn't see much smoke, so I guess things were pretty clean. I don't see why I would need to change the oil. The Foam doesn't even come in contact with the oil. The oil only has 6k miles on it and I'd like to go at least twice that. Do I really need to change the oil?