does all of the radiator water going in the oil chamber???
Kiya hogaya mere bhai, i admit there can be a gasket issue with this but its not the way you are explaining. Nawaz Khan pls check the following.
1) Any leakages on radiator itself, minute/big.
2) Check all the rubber hose pipes in which water circulates, if its company fitted CNG then it must have water supply in the CNG kit as well for trouble free starting issues on CNG in winters. check those distribution pipes as well, also check those pipes which supply hot water to your car's heater (AC wala heater jo ap winters mein use krte hain).
3) when your car is chilled cold, open the radiator cap, fill it with water if its empty and start your car, let the car attain its desirable temperature, do not put in the radiator cap, when it gets to normal hot temperature, look closely into the water at the top of radiator, is it circulating? if yes, it means ur waterbody is absolutely fine, very very carefully take a drop of water from the radiator on your finger and try to feel if the water droplet on your finger has oily effect, if yes than your car has a gaskit issue.
4) get your radiator serviced by a good radiator wala who should open both its bottoms and clean it with acid.
whats your mileage at the moment?