Synthetics and mineral-based lubes absorb contaminants like combustion byproducts, acids, etc. at the same rates. And those contaminants cannot be filtered out by a conventional oil filter. So while the synthetic oil itself
may last longer, it still absorbs contaminants at the same rate that mineral-based oil does which can only be removed by changing the oil.
So the hype about a synthetic oil being able to go longer before being changed is simply a myth. Change the oil and filter together at the recommended and reasonable intervals and your engine will be well protected, synthetic or mineral-based.
Only in extremely cold conditions is a synthetic oil worth it's weight in gold due to its better flow abilities when very cold.