I use sea foam in my tank every winter. 
Seems like there are better options than Seafoam out there. Sadly the good ones don't seem to be available in Europe (unless you're willing to spend an insane amount of money on shipping). After some research my motorcycle buddy ended up buying Bactofin which seems to be a German thing. Let's hope it works.
If the bike is on the centre stand the level is about right.The level in my L2 drops from a small bubble at the top of the glass when on the centre stand to spot on when its on its wheels.
It was on the centre stand when I took the pics, but I'll check the oil level when I check the chain slack, so I only have to de-centre-stand it once. Good thing you reminded me because the mechanic who did the oil change is despite being pretty good also incredibly lazy occasionally and I probably shouldn't trust him 100%.
https://www.stromtrooper.com/threads/clean-oil-sight-glass.431005/ I found this thread about the murky sight glass. Seems to me that it's not a serious issue. I'll try to contain my OCD for now.
