Dex-cool absolutely requires that your system be full at all times, with all air bled out of the system. Air present in the system will cause the Dex-Cool to turn into a sludge, clogging things up and making a mess down the road.

I mention this because we drive Land Rovers. They leak, often times slowly.

The throttle plate heater on my '99 that was completely occluded with Dex-Cool was testament to that fact.

Also, tap water + Dex-cool? Sludge.

Faulty radiator cap? Sludge.

I'm going to go ahead and stick with the green stuff.

 

if you switch make sure you back flush the heater core, I still run dexcool and don't buy into the early head gasket failure theories...

 

When I switched 2½ years ago I drained and refilled the system with water and then drove around or let the engine run long enough that I thought the Dex was diluted throughout the system. I repeated until the coolant looked clear, then drained it again and added two gallons of full-strength Prestone green. IIRC it took three flushes. That's a lot of time to invest, but I think I got all but trace amounts of Dex out of the system.

Someone with more expertise than I may may reply with a valid explanation of why what I did was a bad decision but it's worked fine for me. The color coolant was a little off in the end, indicating more Dex than I thought remained in the system, but no problems thus far. Last July I drained, filled with water, drained and filled with Prestone again and the color is now the proper shade of green.

 

WHAT??? I thought it was a 4X4, no maintenance, racing machine... Dang, I might have bought this by mistake!

Just kidding, LOVE this thing so far. Also, Savannah, those pictures are scary. Looks like they added SAND to the coolant. First thing I did to my Jaguar was to remove and replace the Dex. It came out in a clumpy mess. My heater core was plugged. I think the previous owner had mixed the two coolants. I got to it just in time and it worked flawlessly the rest of the time I owned it.

Last week or so I did the same on the Disco while adding the 180 thermo. It was SUPER clean, clear, and smooth, so I don't think it suffered any damage yet, but glad I'm now using an easy to find and easy to add-to coolant.

 

IMHO "lifetime" coolants, and extreme long interval fluids will make sure that guys like our friend here, Robin Bastid, are never idle.

 

Hehe

Oh, yes, my Trans on the Jag was also "Lifetime", and didn't even come with a dipstick. Guess some 'dipstick' in the engineering department made that decision. I changed the trans fluid immediately after buying it also.

 

It's like water pump impellers in an outoard motor. Built so if you don't change them in the off season, providing a little work for the repair shops; then you can have bigger problems real soon. And who would drive a truck that needed a new water pump every year or two? Of course most outboards run WOT a great portion of the time, as if the fish can't hear that 300 HP closing fast.....

 

When I bought my 01 Discovery last week it was so low on coolant, due to a leak, that I had no idea what had been used previously. I added two gallons of "universal 50/50" so that I could get the truck home. It has sat parked until yesterday when I replaced the throttle body heater and both lines that attach to it. The Asst Service Manager at the dealer told me to flush the system and go back with DexCool. I am hesitant to do that, but what do Y'all think about a good flush and then using Zerex?

 

1. You will find that many dealer proposed solutions are the most costly possible.

2. Here is a TSB from GM on how they advise to flush Dex, just don't re-place with it.

3. Radiator chemistry is enough of a problem on its own, with various chemicals in the water "cooked out" over time. You can find scale buildup in a home water heater, it has neve seen Dexcool, but has been cooking tap water for years. Distilled water should be used to do the final flush out. 50/50 premix coolant, like Peak, is good.

4. Dex takes radiator contamination to the next level because of unintended consequences. No one meant for it to happen this way, they just did not consider all the real world variables in their planning and life cycle testing. What works in a sterile sealed air conditioned research lab frequently has new challenges in the real world.

5. Sludged up rad will usually be cooler on the bottom rows, as they have little or no water flow. These are horizontal row radiators, all tubes are fed in parallel.

6. Here's some pix of Dex mud, and of rad with non-Dex issues (scale, left over stopz leakz). Stopz leakz usually works by sealing a tiny spot in the cooling system with a couple of drops of material. The rest of the jug of majic elixer has to go somewhere, and gravity will take it to lower rows, and sometimes heat will allow a blob to move about like the stuff in a lava lamp (ask your parents). The scale in the rad passages provides small rough spaces for the stopz leakz to seal up as well, hey, it is just doing what it was designed to do, squeeze off small passages.

 

Coming from a Jaguar to a Disco, I have replaced the coolant in BOTH to the Universal Green Coolant. I don't want to stress out about where I'm going to find the 'Magic' Coolant when I'm out in the middle of nowhere.

I'm not a Metals Scientist, so my opinion is just an opinion, but I believe the Green is just as safe in these engines as the Magic stuff as long as you get ALL of the Magic out first. When I bought my Jag, it did have Coagulated Coolant in it due to previous owner mixing the two. I was able to flush it all out over a period of time, and got to ONLY green, and never looked back.

I put about 30k miles on my Jag, and it was as pretty green when I sold it as it was when I put it in.