The best example is what we call vapour pressure. For your car to start, you need some vapour to start the ignition. As the weather gets colder, it's more difficult to have this vapour. The best example of vapour pressure is summer and winter conditions. You have to prepare what we call the base stock gasoline in the refinery with different components so that the vapour pressure meets the Canadian specs. Then your car will start and won't stop on the side of the road. That's one example.
Biofuel composition is another example. Adding more biofuels in a season might mean that the base stock that you prepare before you blend the biofuels would have to be of a different quality, depending on the weather conditions.
Those are two examples—vapour pressure, and the addition of biofuels that would require a different base stock product at different times during the year before it's blended in.