seems like wheel bearing noise and not an engine noise. get it check with mechanic or jack up the car and spin the wheels and feel the vibrations on rims by hand. if there is vibration it means the bearing needed repalcement.
if not, then check the noise in 3rd and 4rth gear at low speeds. if the noise remains at low speed also then it is gearbox noise which cannot be treated unless u get a new gear box or kabuli gear box with a warranty that it will not make sound.
the gearbox goonj issue is common with fx nd mehrans and it cannot be resolved by putting mota oil, surma or banana k chilkey in the gearbox.
