I never thought of using a 10 wt oil in the engine. Keep in mind the "10W" in 10W-30 does not stand for 10 weight. The w = winter, meaning the oil has the viscosity of a 10 weight but has the protection of 30. I plan to run SAE 30 monograde, diesel rated oil in the motor.
I have no issue with the "meets or exceeds" specs. I highly doubt CNH is producing the exact same lube now that they did in 1979 when the tractor was produced and manual printed.
Therefore, that is what I am curious about now. What is the currently in production oil that is the replacement?