Sounds like a bad head gasket or cracked head problem but we really need to know the year, make, model and engine to help you.
Yes! if you have a cracked head chances are your oil and coolant are mixing together and coolant and or oil is leaking out causing the vehicle to overheat... if you have a cracked head fix it! do not drive the vehicle
How to fix this depends on where specifically it is leaking from.
The coolant has oil in it. Possible causes are a failed headgasket, or a leaking oil cooler,
you plunem is leaking and is not chep to fix
blown headgasket
You need a head gasket.
If coolant isn't leaking externally then it has to be leaking internally. A leaking head gasket or cracked head may be the problem. If this is the case, as it gets worse more coolant will enter the combustion chamber or engine oil. Either way you will be able to determine as it gets worse. There will be white smoke from the exhaust. May be intermittent. This is if coolant is leaking into combustion chamber. If leaking into oil, you will notice that the engine oil will have a brown/milky look to it as you check the oil level on the engine oil dipstick.
It is possible for engine oil to float on engine coolant. This occurs when there is a leaking or blown gasket.
The head gasket sits between the head and the engine block if it is leaking out where you can see the coolant, yes you can smell the coolant if it is leaking into the engine no you cannot smell the coolant. You can check the oil to see if it has coolant in the oil if it does then the head gasket might be blown.
If only adding coolant to a leaking system it is safe because soon you will be forced to drain the coolant and fix a problem
You should able to tell if it's leaking so I assume that you are not seeing any coolant where you park so it's a good chance you got a blown head gasket and the coolant is leaking in your cylinders and being burned off or leaking into your oil. Check your oil after running and if it is foamy it has coolant in it.
Perhaps low coolant level This is true, but why???? It's the first sign of a bad intake manifold gasket. Coolant leaking into the oil chambers of your van and into the oil. If this doesn't get fix for about $700, the oil will break down because of the coolant and then the internal parts of your engine will break. New Engine!!!