Delta has now restarted its refinery that it bought last spring, and according to estimates from the airline, it looks like a good move. Delta expects the refinery to cut $300 million from its fuel bill over a year. The move shows how far airlines are willing to go to lower their jet-fuel bills, which often constitute more than 30% of operating expenses. While this is a bold move that should pay off in the long run, Brendan urges long-term investors to avoid airlines. Check out the following video for more on Delta and the industry overall.

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Andrew Tonner, Brendan Byrnes, and The Motley Fool has no positions in the stocks mentioned above. Motley Fool newsletter services recommend Southwest Airlines. Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.