Was playing around with the boroscope I got from Harbor Freight, and had a pleasant surprise. This is the top os # 4 piston. Not bad for 56K miles. 3 of the 8 pistons look clean with the limited field of vision of the scope. Some of the others are are up to 50% covered with carbon. Doing a overnight piston soak on the dirty ones. I’m guessing the lack of carbon is the cleaning ability from switching to E85 9 months ago. 
