The other Mobil 1 oils you might be looking at are the motorcycle oils, Racing 4T and V-twin.
The 10w40 Racing 4T meets JASO MA, but the 20w50 is only API SJ/CF. Neither one claims to meet CJ-4.
If you want a 50 you could run year round (in Florida), Mystik makes a 15w50 CJ-4 synthetic blend I...