You're sending your money down the drain if you're changing, for example, AMSOIL's Premium Protection 20W-50 every 4000km. That oil is good for at least triple that mileage. Your car is an economy sedan and the manufacturer recommends run-of-the-mill 5W-30.
If you insist on maintaining a 4000km interval, just get whatever oil is cheapest. Havoline Formula 10W-30 is cheap, as is PSO Carient Ultra 10W-30, as is Havoline Extra 10W-40, to name a few examples. Even Castrol GTX 20W-50 can be had for very cheap, as well as Havoline 20W-50, ZIC X1 20W-50, PSO Carient 20W-50, Mobil1 Special 20W-50, not to mention good old Delo Gold Ultra 15W-40. There are many, many cheap oils available, all manufactured by reputable companies. There's no need to burn money on AMSOIL or Liquid Molvi or whatever.
I literally have a spare jug of whatever is cheapest to top up any of my cars that burn oil. The cars without catalytic converters get Delo Gold Ultra 15W-40, while everything else gets whatever 5W-30, 10W-30, or 10W-40 is cheapest and available at the nearest store within walking distance.
One Corolla 1.3 that travels on the M2 motorway regularly gets PSO Carient Ultra 10W-30. It has 350,000km. The change interval is 8,000km. It doesn't burn any oil and it works fine.
