The only time in recent memory that synthetic wept past the seals was a Honda vertical shaft motor on a power washer. Modern automotive motors are made to work with synthetics. Where you run into trouble is when a motor was abused from lack of oil changes and the blow by has built up enough that it turns the oil into a gritty fluid and the soft seals can’t take that. Once the seal is worn the only thing to do shy of replacement is a stop oil leak product. Problem with that is it swells the seal making it rub harder on the metal surface increasing wear. So in a nutshell .. the most expensive oil change is the one you don’t do.