yellow color tranny fluid

I'm in the process of putting a belt pulley attachment on my '41 H. (The tractor didn't have a pulley on it when I bought it a few years ago - the farmer I bought it from had flame cut a cover plate).

When I looked inside the opening, I noticed the tranny oil (90 weight gear oil) was a goldenrod color. Not milky white as if it was water contaminated, but a nice yellow, which appears to have plenty of lubricity to it.

More info - last summer I had the entire rear axle apart to replace the axle housing gaskets, so the tranny fluid is brand new, and the tractor is kept in the barn when not running, so its never been in the rain. Is it possible condensation inside the tranny housing has caused the gear oil to turn yellow? As far as I can tell, there's no rust on any of the gears, and everything is running fine.

Comments?

So condensation it is - obviously my hour or so a week at high power may not be enough to get the oil really hot to boil off the water - but it appears it hasn't harmed either my gears or the gears in the picture either!

Thanks for the help... Art

Look something like this? This is what having a hole in the tranny. cover does for ya.