Antifreeze should I flush and change

[JCasper]

I have 50,000 miles on my truck and was thinking about flushing and changing the fluid this weekend. My dad is a retired diesel mechanic and said he doesn't like the long life stuff they put in it. He said he has seen it come out with lumps in it. Kind of like it gels up or something. Is there anything wrong with leaving it in for a while longer.



If I change it is there anything wrong with using just plain old Prestone and distilled water. I was planning on changing the thermostat also.



Thanks, Joe

 

[rbattelle]

I chose to have the local Cummins shop flush mine and refill with Fleetguard Compleat PG premix at about 20000 miles (2 years ago). Why? Because I didn't like the HOAT that comes from the factory. At the time, it wasn't available in most stores and like many other people (like your dad) I was soured by Dexcool.



Having said that, my opinion on HOAT has mellowed out. It's probably a good long-term coolant. Check out the bobistheoilguy.com forums for lots of good technical information on it.



HOAT is NOT Dexcool, however. Your dad was probably thinking of Dexcool, which had a nasty tendency to gel up and turn to goo under certain conditions. Dexcool has apparently been reformulated and doesn't do that anymore.



What I love about the Fleetguard stuff, however, is the apparent quality. The stuff is good until the first engine rebuild at 350k miles. This is the stuff they use in Class 8 trucks, so it's not your "average" formulation. They also sell an "extender" that replenishes the additives in the coolant. You're supposed to add the extender once a year or every 100k miles (whichever comes first). I added a "tiny bit" after 2 years "just in case", but have experienced no cooling system related problems in the last 45k miles.



So whether you "should" change out the factory stuff basically comes down to personal preference. I would do it again. Here's a link with some technical information on the HOAT factory fill.



Ryan

 

[CPittman]

I changed mine at 100K along with the serpentine belt. Just went back with the Mopar HOAT stuff. The thing to watch as the engine ages is the slow coolant fluid loss - I'm guessing mine's weeping from the water pump and eventually will require a replacement pump. The stocker has over 122K on it now, so I just watch it and put in about 4 to 6 oz. about once a month.

 

[jelag]

My 04 now has 211K miles... still have its factory coolant... . we check it every fall, an add back some conditioner that comes from Cummins..... This coolant is approved by Cummins and that's good enough for me... sometime between now and 250 K it will get it first belt and new hoses..... We are having issues with the fan clutch at this time... . and need to deal with that... other wise..... it just keeps on running and running and running... .