it needs CNG setting tappets etc and don't worry mehrans are jinnati cars if they are left parked for a few days then they are different cars then before do tappet tuning etc and july is was far away so do it again
well if u have doubts then change oil i buy from authentic source and never had a problem with zic quality and 60k driven and winters are coming so stick to 10W 40 and caltex is good oil buy form some authentic pump but 10 40 is ok we had a mehran 08 150k driven and still used zix 10 40 if u go for 20w 50 then be ready for early morning workouts by pushing the car
plus also change plugs ngk v power 400rs a set change ignition point 600rs for genuine one and if wires are not ok then change them 700 for set get it tuned by some good pro guys and 10W 40 is what u should stick