Can anyone tell me the difference between these two oils? One is almost double the cost of the other and while I'd lean toward the more expensive one, the assumption being that more expensive means better, I'd prefer that not to be my only reason, lol. The only difference I can see is the A3/B4 designation of the more expensive oil, but not sure what that means for our X5Ms.
Castrol 03037 EDGE 5W-30 A3/B4 Advanced Full Synthetic Motor Oil, 5 quart
https://www.amazon.com/Castrol-03037.../dp/B0161A4CKG
Castrol 03084 EDGE 5W-30 Advanced Full Synthetic Motor Oil, 5 Quart
https://www.amazon.com/dp/B00ICSWGJ0..._t3_B0161A4CKG