Why would oil be in radiator water, running hot, grinding noise

there could be a number of problems as to why there is oil in your radiator and it is important to be aware that your engine will have a serious problem if this happens. Arguably the most common cause is a blown head gasket which runs through the upper and lower sections of the engine. The lower section, also known as the block, contains the pistons and crankshaft whereas the upper section also called the head holds the engine valves. The gasket which holds the sections together has holes in it which allows the engine coolant to circulate around the upper and lower sections as well as holes for oil to flow through. If the gasket blows, the engine oil will enter the coolant passages causing the engine to fail. Moreover, damage to the cylinder connected to the engine block may cause the oil to seep into the radiator. The bolts that hold the cylinder head onto the engine block can sometimes experience wear and stretching which destroys the seal on the head gasket. Therefore, the oil and coolant will be forced to mix together after flowing into the gasket. In addition, if the engine overheats then the cylinder head could get warped and cause the same problem. If a crack appears between the internal oil and coolant passages within the engine block then a problem will occur. The cracks can develop due to a strong impact such as a crash or by the engine freezing which can occur in bitterly cold conditions. Freezing can also occur if too much water is in the antifreeze or coolant mixture which could make it expand and crack

What size engine? The only type of engine that will allow oil to mix into the coolant is an overhead cam engine.... if it's not an overhead cam the ONLY place oil will enter the coolant is in the radiator.... the oil enters the head through the push rods, there is no pressurized oil in the head, if there was a crack in the head gasket the coolant would be leaking into the oil not oil In the coolant. For fluids to transfer, one fluid has to be at a higher pressure than the other the lack of oil pressure in the head and the coolant being pressurized means the coolant would transfer. The radiator however has oil at 30+ psi where the coolant is only about 13 the oil will overcome coolant and make its way in, the tiny amount of coolant that would enter the oil cooler after the vehicle was shut off would most likely burn off in the following trip...... Your "oily"substance could be a film of dirt buildup the grinding could be your water pump and a bad pump will cause overheating

I have same problem this.. my r2 overhead cam engine i change the head gasket and resurface the head making it is flatten evenly. It works for 50km of running the engine the problem resumed.