Jeepwalker

That's right. Metals have different pH ranges where they can remain in a "happy" state. Outside of that range they give up electrons (corrode). Just happens that aluminum's range and Iron's range have a very narrow pH overlap. It's really difficult to keep that narrow pH range. Copper, Brass, nickel are noble metals and even outside their ranges don't give up electrons easily. It's ok if aluminum corrodes away if it's THICK ENOUGH. But where you get to heat exchangers (Radiators/heater cores), where the material is paper-thin ...then you run into problems. When the aluminum becomes your system's anode ...ha ha, doesn't take much to attack the aluminum or solder. Oh ...and the pH scale is logarithimic too!

I used to have customers who had several copper-core heat exchanger boilers for a particular building (in a boiler room ..same system). Some sales guy would sell them a "great deal", "Efficient" aluminum boiler to put in the same hot water system. I would warn the customer, "Hey, it's going to be really difficult to keep your pH in that narrow 8.5'ish range, and most places struggle with that." I've seen enough of that to know what the end result would be. I'd usually get a sad call in about 2-3 years "....hey I need to replace that POS aluminum boiler. ..they're saying $22k to replace the heat exchanger!" LOL. The metals work fine in the same environment as long as they live in a happy pH range (for all metals involved), and proper corrosion inhibitors. But we live in the real world where there are a lot of other things people have to worry about and their vehicle's pH isn't one of them . I do check my vehicles once a yr though. A guy can adjust the pH by adding a pinch of sodium hydroxide (lye drain cleaner crystals) or citric acid (or lemon juice) to go the other way. $12 digital testers on ebay are very accurate (more so than test strips).

Sooooo.... if a guy springs the extra $50 for a copper/brass heater core, it'll be one thing you won't have to worry about for a long time. Not only that, but the passages are different on the aluminum heater cores. The passage count and size are different too (in favor of the copper/brass). But hey, in the end they'll both work ....um, for a period anyway.

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Jeepwalker

I forgot to mention aluminum gives up it's electrons more easily (compared to other metals). Which is why copper and brass make for long-lasting heater cores. Just don't put off antifreeze changes every several years on yer jeep ..as 'Tech' (above) mentioned.








"....it's all ball-bearings these days!"