By brushing the insides of the chuck or spindle, you can prevent premature wear and tear on the internal “fingers” that hold the bur.
First you’ll need a good quality synthetic oil with a high temperature rating, then you’ll want a very small brush that’ll fit in the chuck hole. A few drops of oil in the hole and insert the brush, gently scrub the insides. Use a clean paper towel and wipe the dirty oil off of the brush every few strokes and repeat as needed, until the brush comes out clean. That’s it! You can now put it in your automatic cleaner and autoclave as required.