There appears to be an issue with wizard oils (only tested pre-60 ones so far), not applying to weapons where they should. From what I can gather it appears they have some sort of incorrect hidden requirement attached to them at the moment. For reference, on a level 30 mage, I can apply minor wizard oil (lvl 5 requirement) to https://www.wowhead.com/wotlk/item=1155/rod-of-the-sleepwalker, but cannot apply lesser wizard oil (level 30 requirement), even though the requirements should be met. Similarly, on the same character I cannot apply minor wizard oil to https://www.wowhead.com/wotlk/item=16894/clear-crystal-rod, which again should meet the requirement.
If I had to guess I'd say there's a hidden minimum item level requirement on them currently, where there should only be a maximum.
There appears to be an issue with wizard oils (only tested pre-60 ones so far), not applying to weapons where they should. From what I can gather it appears they have some sort of incorrect hidden requirement attached to them at the moment. For reference, on a level 30 mage, I can apply minor wizard oil (lvl 5 requirement) to https://www.wowhead.com/wotlk/item=1155/rod-of-the-sleepwalker, but cannot apply lesser wizard oil (level 30 requirement), even though the requirements should be met. Similarly, on the same character I cannot apply minor wizard oil to https://www.wowhead.com/wotlk/item=16894/clear-crystal-rod, which again should meet the requirement.
If I had to guess I'd say there's a hidden minimum item level requirement on them currently, where there should only be a maximum.