Should my coolant stick have this on it?..
https://i.imgur.com/PPiJOGQ.jpg

 

Obviously...no. Hard to tell for sure from the picture, but it looks like some corrosion. Worst case is a previous owner put some stop-leak additive in.
I'd drain and flush the system first chance you get. If it's your first time don't forget the block drain in the center iron under the spark plugs. Supposedly any ethylene glycol is OK, but lately I've been using the FL-22 coolant. Comes from different manufacturers and labeled as for "Asian Vehicles"...low on silicates and borates. Do no more than 50/50 mix. Coolant can go acidic over time, and a lot of electrolysis from the bi-metal engine. That's hard on soft seals. Personally I change coolant annually, usually as part of a maintenance routine when it comes out of winter storage here in the Midwest.

 

I flushed a lot of the coolant but forgot to undo the one under the block. Only drained from the radiator. You think that's fine for now until next year?

 

That plastic stick has been sitting in water and coolant for 22 years. Yea it's gonna have some schmootz on it. Mine does too. As long as your coolant in the block and the radiator was a nice green you're ok.