When I was in PK, I used 5w30 in both my 1.6 AT and 1.8 Grande. I was quite satisfied with Total Quartz 5w30, It used to return good economy but it was only good till 6000KM.
Recently my friend using HX7 Plus (API SP, ACEA A3/B4) Its really good and highly specs oil, I would recommend that.
If you still want to use 5w50 then buy it from some reputable outlet. This oil did gave me good fuel economy but drive always felt heavy.
Filter is really important, never comprised on that, I would suggest by OEM filter and get it changed from outside. Parts Central also use to be good back then, I used them for OEM parts in past.