Even if oil contributed to the larger mass extinction, the dinosaurs were dead within hours, not days. The impact alone would have heated the entire atmosphere to about the temperature of an oven.
>The length of time taken for the extinction to occur is a controversial issue, because some theories about the extinction's causes require a rapid extinction over a relatively short period (from a few years to a few thousand years) while others require longer periods.[1]
[1]: https://en.wikipedia.org/wiki/Cretaceous%E2%80%93Paleogene_e...
World wide wildfires, followed by years of minimal sunlight. That would quickly kill most plant life, and 99+% of everything larger than a badger in the first year. Ocean life would be somewhat insulated from the effect and predators can survive on prey or other predators for a while. But, this is not something that got better in the first year.
PS: https://en.wikipedia.org/wiki/Shiva_crater is another contender, but it's almost to large.