@maxud1 Dekho lala any new automobile vehicle launched after 80s never recommended 20w50 as standard viscosity..Hell my daewoo recommends 10w40 oil and that was for 1993..The issue is the manufacturer of vehicle i.e toyota knows well abut the specific oil flow requirements and clearance values.
20w50 is a general viscosity oil used for engines which are old and have clocked over 130000 miles.You engine is new and is in break in period.It is recommended to get you oil changed to 5w30/10w30 asap.You will feel the engine is light and back on track.
Please dont experiment with oil grades.Stick to manufacturer recommended viscosity i.e 5w30..You dealer is a strawbrained bandar.
It is written in the article posted by member mwm749
"To keep engines running smoothly, Adel advises motorists to use the type of lubricant specified in the car owner’s manual."
The article goes against the very remarks posted by @mwm749
Playing with oil viscosity damages engine in the long run.This is my field