Bad engine seal? Bad oil filter? Leaking valve cover gasket?
can exhaust manifold leak cause you to burn oil
engine oil leak
No
oil tanks in ships may leak
they leak oil from the oil pump on the front of the engine
If the casing is spilt a filter will leak an incorrectly installed filter will also leak.
It will continue to leak oil and if you do not add oil regularly it will eventually cause engine damage.
Oil spills happen when people make mistakes or are careless and cause an oil tanker to leak oil into the ocean. There are a few more ways an oil spill can occur. Equipment breaking down may cause an oil spill. If the equipment breaks down, the tanker may get stuck on shallow land. When they start to drive the tanker again, they can put a hole in the tanker causing it to leak oil.
a leak or burning it
if you have a carburated engine the float may be too low or has sprung a leak and sinks in the bowl causing overflow or a leaking injector
An oil leak is always going to be out of the engine as the engine contains oil and the car does not. I think you are saying you are loosing oil with no apparent leak. If that is the case the engine is burning oil and that is why you see no leaks.
It sounds like there may be a leak. If oil is leaking down on the manifold it will cause alot of smoke.