For my rig it's imperative that I see the coolant level that a translucent tank provides. At $30, I just consider it a maintenance item that I'll continually replace for the comfort the quick view of the coolant level provides. At 290k, I'm on the original engine and original head gaskets, which are beginning to weep. I've been running K-seal for approximately 60k miles now and it's keeping the leak to a minimum (I'm adding about a half gallon of coolant/distilled water/year). I check the level weekly and continually on longer high altitude trips.