Yes the oil galleries and piston ports are quite small. However what pieces of filter that may still be in your motor will likely get caught by a good filter. Auto-Rx will not dissolve filter element material. But it will most surely dissolve any oxidized oil deposits safely within the motor. Honestly I believe that any filter element deposits are going to be too large to find there way into an oil gallery. I would perhaps change out the oil on a very short oil change interval before even starting the clean and rinse cycle with Auto-Rx for added insurance.
