Get the rust treated or just spray some rust converter on it plenty of rust converters are available in market now adays and get the car undercoated.(peace of mind atleast for next 3-4 years)
Suzuki dealership used to take 3000/-RS for undercoating about 2 year's back don't know about current rates.
NEVER GET OIL SPRAYED BENEATH CAR NEVER!
Actually car's usually come with some sort of light rubberised undercoating from factory to prevent rusting but here when we usually get our car washed the service station guy's spray oil beneath the car which just destroys that undercoating and the car starts to rust.