Joe, I've researched this quite a bit, and although some people do say they have used the Shell Rotella Synthetic from Walmart successfully in the Sprinter, I've decided that I'm just not going to risk it.
The 229.51 spec is VERY specific and you do run the risk of clogging the DPF as mdpolakow has said above. Yes, you can save...what $50 bucks on an oil change, but, the DPF repair would cost how much ? I've heard $10k.
Up here in Canada, Canadian Tire carries the Mobil 1 ESP Delvac, which I'm going to check out, but, at $45 bucks a jug X3 = $135....yikes. Anyway, we bought an awesome RV, it's worth it to maintain it correctly imho.