Sir dont do that.. you and I bought Taglon 5w50 and now you are going some other grade. lol kidding.
I went for Taglon 5w50 in april or May, keeping in mind that summer was coming with as much high temperature as 47 'C .Taglon is fully synthetic and i believe synthetic oils are good enough. It is a bit viscous but not that viscous that it will create enough load on Engine.
As i said before, i am using Total packing oil 10w40 semi synthetic from day one with simple guard filter in my other ride vitz which is now 150k km driven. Its engine is running as smooth as like running on day one. I never had a problem of oil reduction in it and engine is not giving any kind of smoke at all. So that is why i have a believe on Synthetic oil.