Here is some info Valvoline's web site. Interesting point about the additives since I've never seen it debated here when it comes to OCI's and different brands of oil. The web site is posted below.
"The PAO base stock does hold up longer than petroleum-based oils, but the additives in both wear out at the same rate. The oil companies have tested their synthetics for longevity, but they still recommend following the specific owner's manual for oil change intervals."
Valvoline: Synthetic Or Conventional?
"The PAO base stock does hold up longer than petroleum-based oils, but the additives in both wear out at the same rate. The oil companies have tested their synthetics for longevity, but they still recommend following the specific owner's manual for oil change intervals."
Valvoline: Synthetic Or Conventional?