Okay ..on another board someone linked to this AMC site where one of the members, noted for "repackaging" products and hyping their advantages, displayed a "new" oil specifically designed for AMC engines (a different label on HDEO). Basically everything he said was apparently true about the 15w-40. Later in the thread he mentioned a 0w-50 for a winter oil. Looking at the visc chart ..it appears marginally possible to be below 5w- and at 50 (somewhere around 17 +/- CST) ..but I KNOW that this guy isn't into anything except repackaging. Who makes such an oil? click click!