The Delvac 1 I bought 6 months ago met CG-4, CF-4, but not CH-4. I'm looking at the old bottle as I type. However, the CG-4 meets what my 2001 owner's manual calls for.
Right now I'm using Amsoil HDD 5W-30, which claims to meet both the CH-4 and CG-4 ratings. But Amsoil has not "licensed" their oil with API. This decision has caused strong feelings on both sides; some think Amsoil should belly up to the bar and pay the API fees to get "official" sanctioning showing compliance with the API standards; others argue that this is just money in API's pocket, and proves nothing. I've resolved the issue in my mind by doing oil analysis with a company not affiliated with Amsoil, as long as my test results and wear rates come back good, I'll remain a believer.
Synthetic will give you an edge for cold winter starts in Montana, but even up in Canada many report satisfaction with the 15W-40.