Go back to toyota and slap hard their so called expert who told you to use 20w-50 & 10w-30.
The OEM recommendation is to use 0w-20. But this oil is not successful in PK.
So the best available options are
these oils will give you best fuel economy and very long engine life with protection.
there are many threads here already related to this question. why not search to get more informations.