API (S* or C*) does not put restrictions on SAE viscosity grades -- all monogrades and multigrades are allowed.
ILSAC puts restrictions on SAE viscosity grades -- only 0W-16, 0W-20, 5W-20, 5W-30, and 10W-30 are allowed. 5W-16 is not allowed.
CF-2 oils were mostly monogrades, as oils containing VII don't do well in two-stroke-cycle engines. However, Mobil Delvac 1300 Super 15W-40 CJ-4/SM managed to be certified for CF-2 at one point, but they didn't recommend it for two-stroke-cycle engines despite the certification and recommended a monograde instead.
CF-4 oils certainly could either be a monograde or a multigrade.
Even though API no longer issues licenses for obsolete categories, oils such as SF are made and sold throughout the world.