Brother contact previous owner and ask aboutthe oil grade and brand he was using.
1) if u dont know when oil was previously changed, just change it immediately.
2) check gear oil status. If it is not ok, change that also. Gear oil 2 litre required for mehran
3) check if thermostat is installed, and fan is auto with coolant in radiator (if fan is direct, and no thermostat, thrn install thermostat, put ur fan to auto and if water is in radiator change it with coolant)
Changing radiator to coolant, first get it serviced from good radiator wala.
I know this seems a loads of work for a new user, but believe me these steps are necessary. Yoon smjh lein jo hum ne new owner hote way ghaltian ki the un se app ko bacha ri han.