Chemical synthetic motor oil

I have been keeping an old solid idea that the motor oil brand should not be changed from the Genuine Oil,TOYOTA "Castle" and in case of NISSAN "Elephant".
But, this idea was forced to change by the advice noted through TOYOTA mechanic chief, the recent technology has remarkably improved and the torelance of the motor design and assembly is far smaller than air-cooled VW Beetle period. So, too much biscoelasticity of motor oil is inconvenient for the modern designed motors, more over other than prescripted oil does harm.
I agreed his opinion and my Caldina's oil is not Castle, but Motul 5W-30.

I happend to steal 3 L of Castrol synthetic oil for 4 stroke motorcycle that was prepared by my son for BMW 2 wheel motorcycle, it was just for emergency of depletion of Caldina.
Immediately after starting Caldina, so surprised I wa as to open my eyes fully, how come! The charactor of １AZ-FSE D4 motor has completely changed, smooth, less vivelation, torqueful and powerful!
I couldn't help recommending the great improvement on researdhing and developing in chemical synthetic oil field by the suppliers.