as a rule of thumb, remember (in pak.) once the engine is over hauled, it can never perform exactly same as new engine and it will reduce the oil for sure and also the mileage.
So whatever most expensive oil even you pour, it will be reduced after few hundred km. And it happens only because of serious unavailability of skilled mechanics, and 2 number parts (so called originals). Its really pity, but we have to live with it.
Now as the engine is overhauled, so it will reduce the oil for sure. Not pretty much big, but a significant amount for sure.
as you live in lahore, so try to find the following oils from well reputed shops/dealers.
SIM4 20/50, yellow color bottle. Its SL grade and would help.
or
SIM3 20/50, blue color bottle. Its sm grade and would be suitable too.
Or
PTT Performa 20/50 sm grade.
Or
sinopec 20/50 sm grade.
Or
zippex 20/50 sg or sj grade.
all these oils are mineral but far better than zic hiflow, havoline, shell hx3, pso, etc.
For the safer side, kick out the toyota or suzuki or guards oils and never feed or even look at those oils again.