Your oil tank needs replacing if it shows any signs of damage. A damaged oil tank can not sufficiently contain the oil posing a serious threat. If your oil tank has cracks, rust, or corrosion on the external or internal walls, or if you notice any leaks or spills, you need an oil tank replacement.
However, oil tanks have the potential to last for a long duration of time so if your oil tank is under 10 years old and does not present any signs of damage, it should be okay for safe use.