short answer, yes it matters if you care about the life of the outboard or machine.

If a guy doesnt understand what recycled, short chain, synthetic, zinc percentage, viscosity spread, percentage sulphuric ash, flash temp etc mean to oil than he could probably use a primer in marine trailer bearing grease bases as well. I dont mean to be a smart ass and but theres a world of difference between Texacos short polymere recycled oil they sell at the gas station and Amsoil or Mobile one (I use cheaper 4 stroke oils with similar characteristics like synthetic Castrol in my truck btw). For people that put serious hours on an engine, oil selection becomes a way to extend the life of the engine and save them money on equipment replacements. Quicky blackend oil or sludge on internal parts is the first sign of a crappy low temp oil. large bearing gaps leading to low oil pressure would be the next sign. In a two stroke its bearing slap and exhaust smoke. outboard motors are machines that rely solely on the gas mix oil to stop metal to metal contact and remove heat from the lower bearings. I have an optimax that uses merc DFI oil. If you look up the exact composition of that oil you can see why its more expensive. In comparison to my engines overall or rebuild cost the mix oil is relatively cheap IMO.