Yes, also dissimilar metal corrosion by the minerals accumulating in the bottom of the slowest moving and coolest areas? I once witnessed the large aluminum fuel tank of a boat that was ruined by a penny that someone had dropped into it several years prior. It made a perfectly clean penny sized divot (with engravings visible) in the bottom of the tank. It sure would be nice if there was block drains like the older V8's used to have. Again, several good cooling system guidelines. Periodic thorough flushing with thermostat temporarily removed Completely drain flush fluid Refill with 50/50 mix of distilled water and appropriate coolant only