It appears that a major contributor to the grease shortage is the fire and explosion at the Rocktonm, Il. Chemtool plant.
A devastating fire that started Monday continued to burn Tuesday at Lubrizol’s Chemtool grease manufacturing plant in Rockton, Illinois. No employees were injured, but the company said it anticipated a total loss of the facility as multiple emergency response teams continued working to control...
www.lubesngreases.com
This, combined with a sharp increase in demand as the economy started again, has led to supply shortages.