Amsoil is The First in Synthetics and still the leader PAO synthetic oils are the best type of synthetic oils. Many companies claim to be synthetic but are really highly refined Group III oils. True PAO are engineered for high viscosity index. This means the oils can operate at a wider temperature range without the use of waxes and very limited viscosity additives. Most that are used by Amsoil are temperature sensitive so they do not interfere with cold starts as waxes do. Amsoil also has saturated molecules that will not allow oxygen to attach to them. Oxidizers are still used to make sure the oil will last much longer. Amsoil has nano technology air and oil filters. By Pass Filters that remove more particles to keep the oil virtually clean. And oil analysis as a final safeguard