You need to keep a very close eye on the oil level! Is it overfull now? It sounds like you have added 4 quarts of oil in very few miles! That means it only had one quart of the 5 required! If the fan isn't turning, that could mean the water pump isn't turning either. If the water pump isn't turning you won't get any heat out of the heater. It also means you are destroying the engine due to overheating! Check your belts! IF the belts are good, make sure the oil level is full and the radiator is full, then start the car with the radiator cap off and see if the water is circulating when the water temperature is up to normal. If everything checks out, you might then need to backflush the heater core before the hot water can circulate. First things first though, you really need to cure the oil consumption and loss of antifreeze problems first or it won't matter if the heater works or not because your time will be spent replacing the engine!