Oil itself is a symbol of wealth, abundance, power, and the reserve of riches that has great consequences when it is used or spilled.
It is the anti- heroic representation of abundance in a negative form, and we become acutely aware of the danger associated with it when it spills and poisons the environment. An oil spill in your dream is asking you to rethink your true relationship to abundance, wealth, and power.... Complete Dictionary of Dreams
Dreams of spill signify that you are clumsily revealing your true feelings.
If you are spilling the beans, then this denotes your desire for honesty and the relief that comes when you have nothing to hide. Your dream could be forewarning you to discover a tactful, graceful way to express yourself that is non-injurious to anyone. See Accident.... Strangest Dream Explanations
Something spilling is indicative of wasted resources. It may represent the anguish over losing time or having squandered goods you will miss later. In any case, it reveals a sense of guilt for reckless behavior.... The Big Dictionary of Dreams