can someone explain how the wildly different gearbox oil specs make sense?

[AreWeNotMen]

T'was early on a rainy Saturday morning, and I was doing some light reading in the 2022 Ryker Operators Guide. Interesting reading, but then things get weird and it turns out to be a mystery story! There, on page 119, I discover a plot twist/puzzle/conundrum! As you can see in the attached image, the lubricant specs for the gearbox suggest two very different options for warm temperature operation: 10W50 synth motor oil, OR 75W140 synth gear oil

So, can anyone advise on how these two very different lubricants can be deemed interchangeable by BRP?

And...I wanted to add a poll, but couldn't figure out how to do so. If someone can add a poll to this thread as to which option you will, or have chosen, that would be fun.

PS - I'll go with 75W140 synth gear oil when the time comes