ORIGINAL: SAVAGEJIM

Thanks of the info.

I always hear that; synthetics allow you do go with a much smaller ratio, even 40:1 or 45:1 or much less. But my concern is what kind of residue is left after it is combusted?

I know that lube breakdown is not a concern in two-stroke engine because fresh oil is always entering into the engine because it is mixed with the fuel, even in high temps, the fuel and oil have a quenching effect somewhat, but what the synth polymers breakdown into after combustion is a different story.

Just like you mentioned, residue builds up in the cylinder; namely in the combustion chamber and piston surface because the piston ring cannot scrape those surfaces.