A drill tool includes a bit body, at least one bearing shaft extending from the bit body, and a cone mounted for rotation on the bearing shaft. A first sealing system includes a first annular seal gland formed in a cylindrical surface of the cone and a seal ring retained within the first annular seal gland and compressed against a cylindrical surface of the bearing shaft. A second sealing system includes a second annular seal gland formed in a radial surface of the cone and a Belleville spring retained within the second annular seal gland and compressed against a radial surface surrounding the bearing shaft. A set of non-pressure compensated lubrication channels are configured to supply lubricant to an interstitial volume defined between the cone and bearing shaft, the lubricant retained within the interstitial volume by the first and second sealing systems, the lubrication channels further supporting open air circulation through the bearing when the sealing systems fail and lubricant is lost.