Wat issue u r facing with Atlas Honda Genune Oil?
SInce u are already SF 20W-40 user so dont switch to 20W-50 MG its better to try some xxW-40 with higher API grade & JASO MA tag.
1 of the good & ecnomical oil easily availabe is Shell AX5 15W-40 it wud be ~ 425 Rs liter & if u wana spend more then shud try Mobil Racing 4T 10W-40 that might be hard to find But 1 of the Isloo member @kzest qouted here in forum that it is available with Askari Lubes main distributor in Rawalpindi.
Mobil 1 Racing 4T is fully synthetic & meets API SM & Jaso MA requirments & its price is ~1500 Rs liter. while the Shell AX5 is API SL & Jaso MA complaince & easily availabe in market (Dont confuse it with Shell HX7 which is meant for cars)
I would not recomend u to suddenly swiths to fully synthetic so better u shud try Shell AX5 or ZIc 4T first & if u feel diffrence & like ois perfoamnce then may stay on it or try higher API grades
BTW Zic 4T is API SJ JASO MA complaince & Its SAE rating is 10W-40.