My friend bought a brand new Suzuki Swift on Jan 2001. He changed his first oil after 8000 KM and after that he used AMSOIL 5W30. He left the oil in the car for over 25,000KM. 99% of mileage was on Highway (50-200KM trips) I think he added 0.5 L to top it off. when he changed the oil the AMSOIL was still very clean almost like brownish honey. Back then I didnt know about oil analysis otherwise I would have sent a sample to blackstone. the car has over 100,000K on the clock now and he has only changed the oil 3 times so far. The engine runs just like day one, oil comes out very clean, no valve-train noise, MPG has not changed and it hardly uses up any oil between oil changes! Few days ago he sold the car and it passed emission testing and all with flying colors.