on synthetic I would'nt forsee a problem just a good rinse.
on a side note... most suntan lotions are sold as waterproof so you can go into the sea and swimming pool, but will come off with a 'hot' shower at the end of the day. so i would think a hot rinse would be a better choice. also dipping your suntan lotion bottle in a sink full of hot water makes its thinner and easier to apply.
so i think a hot rinse is the way to go