Originally Posted By: motorguy222
It might be a mistake.
Well, it certainly "might be," though I lean more towards probably a mistake. And this isn't Mobil bashing. I've used a lot of their products and certainly am what one would consider a fan. However, I have never seen a 40 weight certified as energy conserving, and I've been using ILSAC rated energy conserving oils personally and in fleet usage since the designation came out.
So far, I've only seen 10w-30, 5w-30, 0w-30, 5w-20, and 0w-20 listed as energy conserving. Even then, not all of those are energy conserving, if they choose not to obtain the specification or are a dual rated oil with the newer diesel specification.