When I question why 15W-50, they claimed that is recommended from Proton ....:hmmmm:
They must be not studying the Gen 2 CPS manual.
U can show it to them that in the manual stated 10W30. I think in their SC, they maybe only carry one kind of engine oil spec, they must be using same spec oil for all kind of cars. This would make their job much more easier.
What ashame they have this kind of working attitude. With that oil, u may feel ur car more sluggish, but don't worry, it's harmless, but only make your heart feel uncomfortable.
Next time do't visit the SC again,try to go to those which allow u bring your own oil.