coolant low & gunk under radiator cap 2005 GT

**mntnbiker** · 05-13-2013

2005 GT with ~147,000 miles.

So we had the radiator flushed and filled with death cool, new hoses, thermostat, belt, etc. less than a year ago noticed the reservoir tank was empty. I pull the radiator cap to see if I need to add more to the radiator and under the cap I find this

GP rad cap.JPG

What gives with all the sludge? My oil looks fine (not milkshake looking), no check engine light, the car runs just as it did when brand new, no white smoke out the exhaust pipe. My mechanic asked me how the transmission fluid looked. He said sometimes the trans coolers leak into the radiator or vice versa. Can't check that til the wife gets home from work. Anyone care to take a stab at the nature of the sludge in the pic?

Thanks - Mike

**blackgtp95** · 05-13-2013

Its the Dex Cool sludging up happens all the time usually when you mix green with it

Flush the Dex Cool out and redo with good ole green coolant

**mntnbiker** · 05-13-2013

This car came with Dex Cool, and that is what we had put back in it. I also topped it off with Dex Cool

**Below Average Joe** · 05-13-2013

have the Dex flushed out and refill with Green

**Mad Monkey** · 05-13-2013

do another more through flush, make sure to pump out the heater core separately (pop the hoses off and flush)
also before you do this flush make sure you have a metal lim gasket (saw another thread said you were not sure)
the dex can gum up like that from age, it settles in the low spots (rad and core etc) and then can cause big problems later on.

most of us do a very through flush, several times, then switch to green AF. as a personal choice. Dex is fine if its maintained and not going to crap like yours is.

**mntnbiker** · 05-13-2013

Well depending on what my mechanic finds out and if he has to drain the system, I may just have him do a new thorough flushing and refill with the green stuff. What are the pros and cons Death Cool vs the green stuff? Is the Dex supposed to last longer or cool better?

**Oxfire** · 05-13-2013

Some people still like Dex...the vast majority love the green stuff. I personally switched to the green stuff after my LIM job and have seen lower temperatures all around.

**Mad Monkey** · 05-13-2013

cost is one reason ive heard to switch.. green is cheaper.
green cools betters
dex has been known to pit alum.. which ive seen happen but thats usually on crap gummy dex..

make sure when flushing it he does it properly i.e runs the engine with just water etc for a while. bleeds the heater core (in 04+ the core is much lower than rad so it can accumulate)

i would recommend, have him drain it all out, change the lim while your at it, new alum elbows, flush the core the rad etc, go green and never look back