[CSHADES]

That isn't horrible but it is a bit more than you want to see. Also check the voltage from the ground on the battery to the coolant just to see what voltage you have there. I would clean all grounds, make sure you have good grounds from the engine to the body and good grounds from battery to the body. Also flush the cooling system and get fresh coolant in it. DO NOT put a ground on the heater core like Ford tried for a while that will just speed up the demise of your heater core. The lower you can get the voltage to the longer your parts are going to last especially aluminum parts. They can be sacrificial when it comes to electrolysis.