Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Singapore to Mendoza as you normally would.
Related info for your journey
Useful info, stats and facts about Singapore to Mendoza flights.
These are just IATA (International Air Transport Association) codes. They are used in aviation to identify and differentiate airports. That’s why a Singapore Changi Airport to Mendoza El Plumerillo Airport flight would often be abbreviated as a SIN to MDZ flight.