the radiator water in my car starts boiling when the car has been running even for a short period like 10 minutes.but the oil temperature NEVER rises above the middle marker.if you know what's wrong here please let me knowthanxNabeel
from ur post it seems u dont know much about engine and its working.
wat do u mean water boils?do u open up the radiator cap to check :S ?
if u can see bubbles in reservoir bottle.usually means gasket problem
as @hash4u said, its probably the head gasket.......... if this is the case, u will see oil drops in the radiator water ad whitish foam on the engine oil cap(inner side)