Just stick to one brand of oil- Either 5w30-5w40 or Mobil 1- 5w50. They all rock. Changing oil in the summer and winter is no fun and a headache. That's if you change car after 60-80,000KM. If you wanna keep it for more than 1-200,000Km, then keep on changing oils to keep engine in the best condition as possible.
My personal preference;
1) Mobil 1 5w-50
2)LM Synthoil 5w-40
3)ZIC XQ 5w-40
4) Caltex havoline 5w-40
5)LM 5w-30
Then the rest of the okay-ish oils and at the bottom- the legendary 20w50.