most common is to open up da oil filler cap n take a peek inside...dark/black color is not a good sign...ask them to start up da car, check all lights working, water pump, aircond, no white smoke....can check da undercarriage oso..
but i'd suggest to check wif jpj 1st...whether 1.6 can go to 2.0...or check wif runner how much $$ it will cost u for dat upgrade...auto to manual oso might involve a bit of time (getting letter fr jpj) or a bit of $$ (runner)...