When I did my rebuild - KDD Icon heads, Odawg intake, lifters, ARP studs, FICUM, HPOP, LPOP, water pump, fan clutch, blue spring, KC Turbo, River City billet cam, oil cooler, coolant filter, BPD aluminum radiator. . . probably forgot something but you get the idea. Anyway, I switched to CAT EC1 at the time. About 40,000 miles later, I started losing coolant. I could smell it sometimes and the degas would be empty at times. I went nuts looking for the cause but couldn’t find anything. Finally one day on a whim I stopped by the dealer and picked up a new degas bottle cap. Viola!

What I learned is that CAT EC1 doesn’t leave a white residue when it blows out. And that is what I kept looking for. I thought it couldn’t be something as simple as the cap because I didn’t see the residue that the gold coolant always left. Be aware and check the cap! Yes, it could be that simple.

 

That is new one for me and (not sure where you heard this).....red coolant that does not leave a pinkish/whitish residue when dried.....or any coolant that doesn't show a visible trace its been there.

My Mobil Delvac 1 ELC loves to leave a trace of where it wasn't supposed to be. I figure there'd be a clear indicator or a film or something, if it was spewing out of your degas bottle in that quantity.

Sure you're not burning it internally?

FYI:
AI Overview
Caterpillar (CAT) EC-1 coolants (Extended Life Coolants) are designed to be very effective but, like most coolants, if they leak and dry, they often leave behind a white or light-colored crystalline residue, which is a common sign of a coolant leak, indicating minerals and chemicals drying on surfaces. This is normal for coolant drying, but a persistent white crust means you have a leak needing attention.

 

Tried to delete double reply post but can’t figure out how.

 

Actually I never heard it. I observed it. Changed the cap 1500 miles ago and not a drop gone - coolant level has not changed any. That’s over probably 20 warm-up / cool down cycles and with the crazy temperatures this year, it’s been from 20 degrees to 75 degrees. No residue whatsoever.

 

This is also copied from AI:

Yes, any coolant leak, including from
Cat ELC(Extended Life Coolant), will leave a colored, often sticky, residue (usually red/pink) as it dries, but if you're seeing a white residue, it might be mineral deposits from water (if not using premix) or signs of an internal issue like a head gasket leak, not just typical external drying, though normal drying is also whitish/chalky after a while.
What to Expect with Cat ELC (Red/Pink):

• Normal Drying: When Cat ELC (which is typically red/pink) dries externally, it leaves a colored, sometimes gummy, stain where the leak was.
• White Residue (External): If you're using a non-premixed ELC and adding tap water, the minerals in the water can dry white, especially on engine surfaces.
• Internal Issues (More Serious): A white, milky substance mixed with the coolant or on the oil filler cap can signal a blown head gasket or cracked head, allowing coolant to mix with oil.
• End of AI

so what this tells me is:

1.The blown out coolant was red. I couldn’t see that against the black top of the degas bottle. I may have missed the “sticky” part.
2. I was using pre-mix 50/50 so I wasn’t adding any water. So there were no water soluble minerals in water to show up white. This probably wouldn’t occur as much with distilled water anyway but how pure is Walmart distilled water anyway?
3. No white milky substance. No other evidence of internal issues.

Before I posted the original post, I had googled “Does CAT ELC leave a white residue?” AI said no which appears to be an accurate answer to a very specific question. But it didn’t go into detail about the minerals in water, etc. So it looks like EC1 alone leaves a sticky red residue - not readily visible. If tap water is added, it can leave a white residue. It could possibly take more than a casual glance to see issues with ELC.

It wasn’t in great quantities- it was maybe a quart after a week of driving it to work. Just enough to have to keep buying a gallon of coolant ever so often. Just enough to be aggravating. And costly at $20+ per gallon. And every once in a while, I’d catch a whiff of antifreeze. I got tired of carrying a gallon behind the seat.

 

While not a 6.0 engine in this picture, this is what a coolant leak of 6-8 ounces a month, over the course of a year, looks like with CAT coolant. Again, less than a gallon was added over the course of a full year, and to my knowledge none ever hit the ground (just noticed the residue while doing an oil change). This was my son's daily (when he was 16) so you know it was treated real nice and was never hot-rodded or anything.


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When I get home tonight, I’m going to pour out a little puddle of red 50/50 pre-mix ELC and take a pic. Then I’ll take a pic every day till it all dries. Then take another pic after 30 days. If the barn cats lap it all up, all bets are off! 😁

 

It'll likely never dry at ambient temperature, but it'll be interesting to see anyway. Engine block temperature is close to coolant temperature (so 180-200F normally), sure hope the ambient temperature where you live isn't that high.
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Really hope that's a joke!

 

Yeah, that was a joke.