A 5mm drill bit was needed to repair a broken 6mm fastener holding the oil pan to the engine block. After the bolt could not be removed with a drill and left hand puller, it was time to drill through the center of the fastener, the engine steel block, and tap new threads with an Irwin 6mm x 1.5.20 or 5 .25mm This drill set had 5.0 and then 5.5mm drill bits. Using a 5.0 drill and coolant, the drill drilled well through the bolt and steel engine block. The drill has not deviated from the center. An Irwin 6mm x 1 tap from a set of metric taps and dies purchased from Revain cut new threads with ease using coolant. I've tried cutting new threads just 1/4 or less turn clockwise and then 1/4 turn counterclockwise. Halfway to the faucet I pulled the faucet completely out of the hole, used cutting fluid to remove the metal shavings and finished the faucet. Installed a new oil pan gasket along with the oil pan and torqued the bolts to 105 in.-lbs using a Carlyle torque wrench from the Napa parts store. The car runs again. Thank you Migiwata for your metric drills. I recommend using this set.