It was leaking from under into the ground. The mechanic said he changed the tube.that connects the coolant Tank.

Need advice.I got a leakage from the the coolant took the car to a mechanic and this was fixed when I got home and checked the coolant the following morning.there was oil in it.The car is not overheating, The engine oil is the same colour and the coolant does not bubble when opened. Will appreciate ...