gear oil weight

What is the right gear oil weight for the warmer months. I haven't changed it it sometime now. Thanks

I usually use 80w-90 all year round. What does the owner's manual say?

80W90 is what the older FSMs call for. Newer FSMs call for 75W140 synthetic. Gears havn't changed, so it's a matter of new products being available now.

80W90 conventional is okay for most uses ... that's all we had for a century or more, but for heavy use and for towing the 75W140 synth is a better choice.

The 75W140 synthetic is also very expensive and somewhat hard to find. As long as it is changed periodically, stick with the 80w90 conventional.