A quick look on the QS website states the following concerning SN Plus: "The following Quaker State products are all licensed by the American Petroleum Institute as complying with the specifications of the new API SN PLUS category:
Quaker State Ultimate Durability Full Synthetic Motor Oils - SAE 0W-20, SAE 5W-20, SAE 5W-30 and SAE 10W-30
Quaker State Synthetic Blend Motor Oils - SAE 0W-20,SAE 5W-20 and SAE 5W-30.
Nothing on the site suggests that conventional oils meet the SN plus.I would guess that it takes a semi or full synthetic to meet the SN plus spec.
2009 Sonata :189K
OCI 5K using the cheapest dino oil I can buy,usually NAPA or TSC Travelers oil.