Glazed carbon build up on pistons Toyota Prius wrong fuel mistake

UPDATE 4 (reposted from below) The stuck rings allowed the oil to be contaminated this was new oil as well Fortunately the engine only needed new rings as one was broken, all the bearings were as good as new on the 110, 000 mile engine, some noticeable piston skirt wear which was different for each cylinder caused by the blocked oil holes in the skirt its self rather then age, but the pistons were reused and the engine, now at 130, 000 miles is running a treat. The bearings really did look brand new th