You cannot directly compare the degradation rate of the EV oil with that of the Gulf oil.

The degradation rate is highly dependent on temperature and UV exposure. The Gulf is way hotter and sunnier than Prince William sound.

The oil is much lighter in the Gulf and much of it evaporates. It starts a lot further offshore and has a lot more opportunity to degrade before it reaches the shore.

Still, the sheer volume of the Gulf spill ensures that its effects will be with us for a long time.