Synlubes answers sound fishy to me. Even if the oil didn't break down, gasoline would eventually contaminate the oil. I think this happens because of blowby (combustion charge blowing past the piston ring and into the sump). Usually gas will burn off once the oil reached operating temperatures, but if somebody only drives short distances, this will not occur.

Also, the "TriMagnet" may not be too beneficial in a Civic since the block, heads and pistons are aluminum. Hence, there's no ferrous metal flakes for magnet to capture.