While the world outside WoW contemplates the future of the petroleum industry, casters nurse their own form of oil dependency: mana oils and wizard oils. Heck, if you're an enchanter, you may even be hooked on both! These weapon-buffing beauties boost various combinations of healing, mana regeneration, spell damage and spell critical strike rating ... juicy stuff for casters.
As with many consumables, The Burning Crusade era ushered in an enhanced rung of these weapon-buffing oils. Yes, they're higher level than the older versions ... But as Blizzard is so fond of reminding us, bigger is not always better. Most players seem to prefer the older oils, which offer the stronger oomph of two effects instead of one. However, today's shift away from Old-World components (in this case, the relative difficulty of obtaining Large Brilliant Shards in a post-Burning Crusade economy) stymies many an enchanter seeking to make and market oils, as well as many a consumer seeking an affordable way to buy them.