Low-Temperature Performance Advantages for Oils Using Hydrodewaxed Base Stocks

Single and multigrade engine oils formulated with catalytic hydrodewaxed (MLDW) base stocks possess low-temperature fluidity properties superior to counterpart products using conventional solvent dewaxed base stocks. This low-temperature benefit for MLDW oils is demonstrated in CCS and MRV viscosity measurements and cold engine cranking studies. This advantage is a natural consequence of the composition differences imposed by the respective dewaxing processes. The MLDW process is more selective and more efficient than solvent dewaxing in the removal of paraffins to reduce lube oil pour point. It follows that MLDW oils have fewer paraffins available for wax-gel formation at low temperatures. The lower paraffin content is also responsible for the lower VI values for the MLDW base stocks. Thus, the superior low-temperature performance of MLDW oils is contrary to viscosity-temperature extrapolations.