What is the Best Cutting Oil for Drilling Metal?

Project Farm tests several products to find the best cutting oil for drilling through both mild and hardened steel, including:

• Tap Magic Cutting Fluid,
• CRC C3400 Truetap Cutting Fluid,
• Rapid Tap Cutting Fluid,
• CLI Syntec Premium Metal Tapping Fluid,
• Lenox,
• 3-in-1 Oil,
• used motor oil,
• bacon grease, and
• shortening.

Brand new twist drill bits were used for each product tested. In a recent video on twist drill bits, DeWalt and Bosch did well but using a high quality cutting oil helps a lot.