The most important part of the Auto-Rx process requires product for the maintenance program. Purchasing only two bottles for sludge issues makes this necessary application impossible. Please be sure to follow application directions on www.auto-rx.com as opposed to any auto message boards. Frank Miller Inventor, Auto-Rx
If your engine needs to be treated for sludge , group 111 oil is fine year round. Synthetic is not for sludge issues. Sludge is a 3 bottle application.
