Antifreeze brown sludge

You have an oil leak into your coolant system or the previous owner used plain water in the radiator and that's rust. Maybe it's both.

Any chance this "brown stuff" comes in a bottle that says "Bar's Leaks"? It's usually used by cheap bastards that don't want to pay for a proper repair. Yes, it generally works if it's a small enough leak, but as you noticed, it tends to make a mess of everything, and can even block the small passages in the radiator or heater core.

If it is Bar's Leaks that you were told to use, usually one bottle is enough, depending on the size of the engine, and the rest of the fill is regular antifreeze.

Is this car a recent purchase, and who told you the "brown stuff" has to be used?

Yes great for clogging heater cores.

I have to admit that I am a cheap bastard and have used a stop-leak product . I suppose that changing the head gasket on a Dodge V-6 truck wouldn't be too difficult but the truck was marginal at best. The radiator was flushed and replaced with water and a can of stop-leak was added. After 500 miles, the radiator was flushed and refilled with antifreeze. That was a couple of years ago. The truck has developed a problem with the door hinges and the windshield has a crack in it so it's future is uncertain but I can't compla in about the engine.

No the brown antifreeze comes in a regular size antifreeze jug. It looks like very muddy water right out of the jug.

I've had it five years and don't remember who said that. Before this I had a 1992 that didn't run so hot. Whoever it was said that green antifreeze is not for engines that normally run higher than the boiling point.

That would make sense. Does oil mixed with antifreeze normally turn to thick, almost hard, sludge?

I'm not a dentist, and I don't play one on TV, so before I complain that getting details is like pulling teeth, what DOES the jug say, and is this a NEW jug you just bought?

Normally, antifreeze starts out clear, and is dyed to show what specific formula or car it's intended for. You'll find good old green, as well as yellow, amber, blue, red, orange, pink, or whatever other color is popular with the hipsters this week.

Mister Internet (still self-identifies as male) thinks your 2002 Buick likely originally used GM's "special" Dex-Cool (bright orange). If somebody poured some of the old-fashioned green in with Dex, what you can get looks like lumpy brown sludge smeared all over the inside of your radiator. Doesn't flow or cool properly afterwards. Complete flush and refill with new would be needed.

It said 'antifreeze' and no, what I just bought is green. I swear the old stuff was dark brown when new.

It probably said Dex-Cool but can't be sure. That does ring a bell. Are you saying the stuff is known to make sludge when mixed with the old green stuff (even without a possible oil leak)?

I've never seen that. Mostly, it looks and feels like brown mayo. Tastes like it too. :)

Are you talking about Dexcool? What exactly does the owner's manual specify?

Umm... all engines since the Model A have run higher than the boiling point of water at atmospheric pressure. It was a big advance over the Model T system, too. The whole idea of keeping the system under pressure was really pretty revolutionary.... but these days it's pretty normal.

Look in the owner's manual, what does it tell you to use? If it says to use dexcool, use dexcool. If it says to use standard green stuff, do that.

--scott