80mm Sunon ball bearing vanilla flavor work fine. Just be sure to get low wattage('bout' 2.1) for silence. They still run at about 2,800Rpm and cool well.
Sorry,,have to disagree with using WD-40 to oil the bearings. It will gum-up at high speeds/heat. Would suggest you use a good machine oil instead. Believe it or not,one of the best is 'Hoppe's' lubricating oil. High viscosity,but won't gumup. They recommend it for electric motors and so do I...