not if its a later cabby like this one, they use oil/water cooler just like MK2 GTI. prime suspect if you have oil in your water. to confirm, remove the 2 coolant pipes from the oil cooler and bridge them together. flush coolant system and see if oil comes back after a week or so of driving, plus oil leaking out of the oil cooler pipe connections a givaway its bust.
to get oil out of the coolant system drain the coolant by disconnecting as many pipes as you can, then flush with a hosepipe till water is clear. connect it all back up and fill with water plus a cup full of bio washing powder. run engine till hot, then allow to cool, drain and flush. repeat till oil is gone. drive car for a week with plain water in it, see if it goes oily again after cooler is bypassed