if a clogged heater core isnt a big deal then no its not. as far as the coolant level, it should never go down. unless its boils out, leaks or burns off.I read posts here contending Vulcans tend to get rusty coolant. Basically, the posts indicate it's not a big deal.
I have a question for them. When coolant turns brown, does the coolant level go down, too?