Lubricating Skate Bearings
A sealed and greased bearing is preferred to one that is oiled due to the fact that skateboarders simply do not clean and re-lube at intervals even close to necessary for oil use. Meticulous racers should run an oiled bearing, but only if they clean and re-lube throughout the day. A greased bearing is basically maintenance free, but can be cleaned and re-lubed if need be. See SKF's site HERE for cleaning details. The bearing cartridge is not to be packed full of grease, only enough to coat the actual balls (20% of open space). To much grease causes unnecessary friction. NTN has an excellent article on bearing lubrication HERE and another article on care and failure analysis HERE. Torco has an informative artical on grease HERE. SKF Grease LGLT 2, polyalphaolefin (PAO) synthetic base oils grease with a lithium soap thickener (NLGI Grade 1.5) is considered the standard bearing grease for general skate use. This is some expensive stuff. Maintenance Products Direct caries it and it sells for $80 per 1.0 kg. I have a tub of this an would be willing to sell some.
If oiling bearings for max speed, exactly 2 drops of an ISO 13 oil should be applied. may be ok. Basically you need a grease rated at MIL-G-23827. To understand some more details regarding grease specifications read THIS.About the best way to get grease or oil into a skate bearing is by using a syringe. I found some cheap suppliers online. Microtools has a good selection, at good prices, with a variety of needles to choose from (15 guage works well).
