I've seen some crazy crazy messes from dexcool, mostly from systems that were never changed high mileage situations. Engine-cooling system so eaten up not salvageable. Open the rad cap and its just packed with orange crap...............

 

My experience with all coolant

Dex cool works fine. My wife's trans am sat for a long period of time, the dexcool turned into sludgy substance and we found moss or some sort of algae growing on the overflow dip stick. That water pump seized and the cooling system needed several flushes.

I've also had several gm vehicles go into 300k miles and never had a flush. It seems more of a factor that the car be driven regularly than the coolant type

The green universal parts store stuff is not extended life and has a shorter service life. It is fine to run in most cars, in a heavily used vehicle it can break down quicker and require a flush more frequently than a long life coolant like prestone yellow or other universal long life coolants

Bmw blue / pentofrost blue
I used this in a honda and experienced a much more controlled cooling system. I could set my watch to how the car warmed up every day on my commute. What I also found is that the coolant is almost an ultra fine liquid. It was a very greasy substance, and my honda experienced a leaky o ring to the water pump pipe that went away when the car was switched back to a standard long life coolant.

The other types of pentofrost, or specialty, or as described on the bottles, super extend life coolants:
Red - toyota.
Pink- toyota / vw audi
Blue - newer nissans, hondas,

I've noticed older 2000's models camry's come in with 200k miles with zero maintenence and an absolutely bright pink coolant in the resevoir.

So you can switch to the specialist colored coolants, it's been my experience the blue coolant is a much finer coolant, and much more consistent with heat dissipation than a standard long life coolant. A word of caution from my experience is that the blue can cause small coolant leaks in a system with old dry gaskets. It's also extremely "greasy" and hard to get off of your hands lol

So in an ls with an easily serviced cooling system I say go for the blue. In my dsm where a water pump leak could kill an entire weekend, I go with the universal long life yellow

I don't believe the blue works any better at cooling, but it is a much finer substance and definitely lubricates the system better than most universal coolants

 

The greasy feeling you're describing is the surfactant. It makes the coolant "wetter". Same thing soap does to water. It breaks up the surface tension so the liquid will penetrate surfaces better and stick better. Helps with heat transfer and as you noticed works as a lubricant. As well as help it find smaller holes through which to leak

 

The thing about it is that this is a V6 car without a PS cooler in the coolant loop.

 

My '98 sits most of the time, always for about 6 months every winter and then only used maybe once or twice per month in the spring/summer/fall. It's had one full system flush back in 2005, and since that time only basic radiator drain/refill cycles every two years (which swaps out slightly less than a gallon each cycle.) No complete flushes since '05. All of this is with Dexcool, premixed with demineralized water. The coolant stays clean, the radiator is clean, the heater works great, and the entire cooling system is assembly line original with no leaks or issues at all.

I don't see disuse/seldom use as a problem for Dexcool, just as long as the system is still maintained properly. If the coolant was already old or contaminated in some way when the car went dormant, then I could certainly see some issues developing.

 

Cool. Then it's not PS fluid and you've got one less thing to worry about

 

Hers sat outside the whole time for 2-3 years. Contamination along with stagnation equaled death to the system

 

I'm following the RPM WS6 method with a radiator drain/refill with Dexcool every few years. The system was thoroughly flushed in 2012 and everything inside the radiator looked fine when emptied. I was a bit concerned since that fluid was likely the factory original fill at 14 yrs old (12K miles on it). The car sat a lot. When I tested that old fluid for voltage to ground it came out very poor. And the look of it was a murky brown wit a slight tint of orange, though no floating sludge. I'm sticking with Dexcool since it's had to adverse effects on my system.

I'm sort of surprised that the common green stuff is purported to give better cooling. It allows a layer of chemicals to build up on the engine's cooling surfaces. The Dexcool doesn't do that. Even though your coolant could be running "cooler," that doesn't necessarily mean your heated engine metal temps are cooler. And that's what you're trying to protect. Unless you have RTD's mounted in the engine cyclinder walls/bearings, you don't know if your choice of coolant is doing better or worse than the next brand.