Hapco Rack And Pinion Formula eliminates steering stiffness and noise instantly! With just one treatment, it also effectively protects all power steering systems against heat and wear. Compatible with all types of power steering fluid, will not harm seals and does not contain petroleum distillates. For Best Results: Add one 8 oz. bottle of Rack And Pinion Formula directly to power steering fluid reservoir. Start engine and work steering wheel its entire range several times to circulate fluid throughout the system.