Always go by the highest rating on the label. The SM rating supersedes SL; SJ, SH, and SG. Oil technology is advancing at a tremendous pace with five year old technology already being obsolete. Unfortunately motorcycle specific oil is not a high (or medium) priority for refineries. Finding an appropriate oil for an air cooled motorcycle with a traditional wet clutch is becoming more difficult every passing year. The sad part is, old technology works best for our Savage. An oil with a SG high rating is a good match for us. I can recall years ago, when it was not recommended  to use SJ oils in a motorcycle. Unfortunately we can't stop advancements so the newer upgraded ratings are what we have to deal with and not always the best solution  for our bikes. The higher API ratings generally mean more lubricious which is good for the automotive industry and not necessarily so good for us. That being said, I personally believe Mobile refines the best oil in the Industry, but they are not doing Savage owners any favours.

I was under the impression there were no motorcycle specific oils later than SG.

Clive W