A new class of Lubricant Oil Flow Improvers (LOFI) was developed using statistically-based molecular design techniques, employing model compound studies and fundamental mechanistic understanding. These LOFI's were designed to be effective in a broad range of solvent- and catalytically-dewaxed basestocks, including API Group II and III hydrocracked stocks.
Basestocks for crankcase oil formulations are changing in composition. The volume of hydrocracked basestocks is increasing, realtive to solvent extracted basestocks. New dewaxing processes have been successfully introduced, such as catalytic dewaxing and catalytic iso-dewaxing. These process changes, and increasingly varied crude sources, lead to significantly different types and distributions of wax in the basestock.
LOFI'S, also called pour point depressants, optimized for traditional solvent-extracted, solvent-dewaxed basestocks may not work efficiently in these newer stocks, or may not work at all. Conversely, LOFI's designed for the newer basestocks may be ineffective in the more traditional basestocks which still dominate the market. An ideal LOFI will be able to treat both types of basestock with a wide range of viscosity modifiers, to maximize formulators flexibility.
The traditional empirical approaches to selecting LOFI can require excessive time and test costs as the basestock slate becomes more complicated and new test requirements are introduced. The design and selection approach presented here is based on the use of model diagnostic compounds which maximize the response of oil formulations to the molecular parameters of the LOFI. These parameters include molecular weight, average carbon number of the side chains, and the distribution of side chain lengths.