Blown head gasket, cracked hed or cracked block
There are a couple of things that can cause oil to get into your coolant reservoir. A blown head gasket or a broken piston ring are the most common causes.
The oil filter on a crafter is to the left of the engine under the coolant reservoir.
Do you have an oil cooler? I have heard that is a possible cause, as would be the head gaskets.
if there is oil in the coolant system it could be a crack in the intake, a ruined intake gasket, a cracked cylinder head
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.
The reservoir automatically replenishes oil in the oil pan if it is burned away. It was made for the consumer who doesn't change oil regularly.
On a 2007 Ford Expedition : The engine oil dipstick is on the drivers side of the engine near the engine coolant reservoir and the brake fluid reservoir
Down on what? Engine oil, check the dipstick. Coolant, check the reservoir.
The oil in a 1993 Isuzu Rodeo is put into the reservoir that is located on top of the valve cover. There is a cap that has to be rotated to remove it.
Most likely you have a gasket breach (leak) where a gasket seperates a coolant path from an oil path. This is usually in the head of an engine. Do a cylinder compression check.
If you mean coolant in the engine oil reservoir, then yes, it is slightly possible, but very unlikely, that the engine block water jacket has developed a hole between the water and oil pathways. Other than that, the head gasket is the only place where oil and water can come in contact with each other unless your car is equipped with an engine oil cooler which is internal to the radiator (very unlikely). If you are referring to coolant being in the radiator overflow reservoir, it is supposed to have coolant in it. When the engine is cool, the overflow reservoir should be around half full.
This would be a primary symptom of a blown head-gasket.