Inverter Coolant Tank -- Broke or not?

I was out braving the gentle winter breezes this afternoon, checking under the hood and -- like always -- was unsure if the inverter coolant level was low or not.

I find it easier to tell if I unscrew the cap and look inside. So, I start to turn the cap. It was very tough to turn. In fact, I got nervous, thinking to myself, "this is how it comes off right? Am I breaking something?" It stayed that way through about 2/3's of the removal.

Well, it came out. It had a bit of white crust around the inside of the neck of the tank and some on the threads, which I assume was what was causing the "stuck" cap. Not a lot, but you could certainly see it.
The car has had a thin crust of this stuff around the outside seam of the tank for at least 30K -- you know the seam that goes all around the tank and makes it tough to see if the coolant level is right to the top....

That had appeared before I took it in for the inverter coolant recall thing several years ago, IIRC

Coolant level was fine and has always been fine. No codes thrown and the car runs fine. It has about 80K.

Last time I drove it was three days ago. As an aside, as I was removing the cap, that "rattlesnake sound" the car makes came on for a bit. But that sound seems to crop up all the time.

So, I am leaning toward, ain't broke, don't mess with it....???? Are these caps like the radiator caps that need replacing every once in awhile?

And, yes, I spent half the afternoon googling for anyone else reporting this and found nothing before I gave up and decided to post.
Kris

 

Patrick, Patrick, Patrick:

Thank you so much for your reply!

I was getting a bit worried about it the more I thought about it. But, your answer has eased my worries!

I will scrub external deposits off in the next day or so, I think I may have a window on Monday before the ice and snow begin again!

Kris