Dura Lube HL-41701-12 Engine Treatment Booster - 8 oz. Dura Lube Engine Treatment Booster is an advanced synthetic formula that works with all motor oils, engine treatments and oil stabilizers to rejuvenate and extend performance It removes sludge and varnish buildup caused by the over use of oil stabilizers DL Booster replenishes key chemicals that help maintain a higher lubricity which reduces friction, heat, wear and returns the base product to its original strength or better Dura Lube engine treatment additive is a precision blend of high tech compounds Protects your engine and gets the most from its performance