Yes, although perhaps not in the way you would expect. When heating oil experiences low enough temperatures, the oil’s paraffin content will start to gel. This begins to happen just above the standard freezing temperature of water, and at this point, the oil will condense and cloud, although performance will not be affected. However, once temperatures sink to around 15 to 20 degrees Fahrenheit, the paraffin separates and crystallizes, turning into a kind of gel. If your heating oil gels, it may start clinging to your tank’s sides and may gum up your entire system, drastically altering your heating system’s flow rate. If this happens, you will effectively have no heating source, which is why preventing this situation is so important.