There are two ways of extracting canola oil from seeds: one is by cold-pressing (which is expensive and harder to come by), and the other is by gently heating the seeds and using a solvent (usually hexane) to extract as much oil as possible. A tiny trace amount of hexane remains in the oil after extraction (it accounts for less than 2% of our daily intake and has a good safety profile), so technically, the later method doesn't produce pure canola oil.