Here is an easy tip to keep your drill bits from overheating. Of course nobody here would push on their drills hard enough to overheat the bits, so this tip is for extended projects with many holes being drilled. Keep an ounce or two of antifreeze nearby in a cup and dip your drill bit it in every minute or so as you proceed with your project. No need for extended life or expensive stuff, just use what ever is lurking in the corner of the garage from one of your watercooled cars. It works great and quickly cools down the bit.