Chevron would be an obvious strategic buyer as Chevron has failed to establish a strong consumer brand name for its lubricants, even though they are well regarded by insiders. Last year's effort to establish Havoline as a premium consumer brand didn't work.
Shell bought Pennzoil and Quaker State for just this reason. Likewise, BP bought Castrol. ExxonMobil has the strong Mobil-1 brand and really doesn't need another consumer brand.
I'm not surprised Ashland want out of its only consumer business segment. Business-to-business selling is a whole different animal from the consumer game, and a company which is great at one it rarely great at the other.