So anyone know what exactly MS-12633 says? The reason I ask is because Castrol Edge 0w40 is made in Belgium and is a group 4 synthetic available easily at Wally World for $26 for 5 quarts. It's CN rated. I know Penzoil can be had for under $5 a quart if you play AMAZON's price game, right now it's about $7 with the rebate. Any thoughts on using a non MS-12633 oil? Anyone run the Castrol Edge in their 6.4L without the engine exploding?