Yes you can. You could have a cracked head or engine block. In some cases the head gasket or intake gasket could be defective. Also check to see if your Transmission Fluid is low as the fluid passes through the radiator for cooling. If the cooling tank is cracked then it can enter the radiator.
Yes.
your radiator needs to be replaced
If there is oil in the coolant reservoir that means that the oil has gotten into the cooling system. The most likely place for oil and coolant to meet is at the cylinder head gasket. I hope this isn't the case because it's a very expensive repair.
if there is oil in the coolant system it could be a crack in the intake, a ruined intake gasket, a cracked cylinder head
Nothing will happen if you drain the cooling system and replace the coolant.
There are two possibilities, one it is most likely the automatic transmission cooler( in the radiator) is leaking transmission fluid. The other, engine is oil entering the cooling system through a leaking headgasket, cracked cylinderhead or engine block.Keep in mind that the engine oil pressure( normally) is allways higher than that of the coolant system , when engine is running.It is rare but possible that engine oil @ say 40 p.s.i. is entering the coolant system, but when the engine is shut off the coolant system pressure is not high enough to leak into the engine oil .It is not uncommon for(in radiator) transmission coolers to leak oil into the coolant system.
Any time you have water/coolant in your oil, look for a malfunction in your cooling system. A cracked head is a great place to start.
if you have antifreezecoolant in your oil you need to tow your car to get it fixed
A broken piston ring can allow oil to get into your cooling system. A bad valve seal can also allow oil into the cooling system.
If it is an automatic transmission, the cooler in the radiator is most likely leaking into the coolant system.
it is common for this to be a head gasket but if you do not have oil in the coolant or coolant in the oil i would start with the thermostat. if your engine temp. is higher then normal this would be a good place to start.
There are several drain plugs on that vehicle, radiator (coolant), block (coolant), engine oil, trans oil, etc. There are usually located at the lowest point of that particular system.