As you are paying for your oil when you place the order, we charge you for a specific volume. We are not subsequently able to take more money from your card therefore it is not possible to have your tank topped-up.
While suppliers appreciate it may not be possible to determine exactly what your tank will hold, they do ask that the order is for a specific volume of oil rounded to the nearest 100 litres. If the tank can't take the full volume ordered, you will be refunded accordingly. However, you may be charged an under delivery fee for the fuel not delivered, we would therefore recommend you do not over order if you are unsure how much your tank can take.