101400KM mileage is nothing for an engine to require overhaul : (
however, since there are lot of fake engine oils availble in our market, maybe that's the reason your engine got messed up.
get a few more opinions from reputed workshops near your area before going for overhaul.
timing chain or belt engine, overhaul should not be a difficult job for a person who knows what he is doing.
my car (Swift 2013) got heat up twice, is reducing coolant from reservoir, engine vibrates a little, but still no oil reduction or smoke from exhaust.. it is at 124000 km mileage; however, i bought it used (and i am sure pretty much abused at that time) so i am not the first owner or know the history of the car so cannot complain about engine health now after two heat-ups..
mechanic is also telling me to get the head gasket changed (and potentially more expensive jobs when the engine opens) , but since the car is still not giving smoke or reducing oil so i am hesitant to let him open the engine.