JobbersWorld, which is an independent newsletter focused on lubricant distributors, recently published an article explaining the answer to this very question. The article touches on the increases and decreases over the past few years and then goes on to explain the reasons why crude oil prices are one of the primary factors driving base oil prices, which typically drives lubricant prices. Reasons include OPEC pricing, global supply and demand, geopolitical unrest, natural disasters, accidents, production costs and storage capacity, power outages, plant turnarounds, and others.
So, what is the reason for the recent round of lubricant price increases? This link takes you straight to the JobbersWorld article.