I just drained my drive oil on my Bravo drives. The oil in the starboard drive looks almost as good as when it went in, nice green color. The other port drive oil looks a little dirty or dark. Both the lower and upper magnetic drain plugs looked normal, a tiny bit of fuzz on the lower no metallic particles. No water in either drive.

The oil on both drives has 50 hours, not run hard, the total time for both drives 580 hours. I have always used Mercruiser Drive oil.

Just curious what other boaters have experienced with twin drives, do they both always look the same?

Darker oil indicates a heat issue. If you were to monitor oil temps, you may see a difference. Why it happens is another story. It could be a wear issue or a water circulation problem. But with 580hrs total, things could be worn and causing heat. It might just be time to have them looked at. The normal fuzz on the magnets is metal that circulates thru the tapered bearings and causes dents in the races and rollers. This could be a source for heat if one drive is worn more than the other.
Keep an eye on things, and I would change the oil more often. Maybe just that drive if you see it is a bit black. If the other one is green after a few ounces come out.. Maybe plug it and add some and run it the 50hrs.

Dick