The problem is the ecu runs to much timing because Japan has higher octane fuels then us and on our fuel it detonates and causes bearing damage and sooner rather then later bearing knock or a hole in a piston
The other thing to consider is this the fg xr6 turbo or the turbo fitted to everything else. Cause the the fg xr6t had a smaller turbo then all the others
He is saying the left over petrol will cause it to read a lower ethanol content which will make the sensor wind back the tune (reduce timing) even though the contamination is so little it won't effect the knock resistance of the e85