Went to dealer yesterday to buy coolant; when he asks what I’m going to do w/ it, I tell him that I’m going to do a flush and he says that all I need is 2 gallons and it’s a total of 4 gallons in our trucks. We go back n forth a little and I told him I wanted to do some more research and then come back. I get home and finally look at the manual and it says 7 gallons. This is just the parts guy, but he swears up and down that their books say to flush only 4 gallons. Am I missing something? From what I have read on this site it’s agreed that it’s 7.

 

He's probably reading the section on drain and refill, not flush.

 

If you drain with the radiator plug you will put back in a little over 4 gallons. No real need to flush the block. So 2 gallons is correct. Just crack the drain plug, don't take it all the way out, and take off the radiator cap.

 

Buy it at NAPA, Zerex G-05 is the factory fill (different color) and much cheaper.

https://www.dieseltruckresource.com/...n-t262131.html

 

just had the coolant changed in my 2005 dodge diesel.

I bought 3 gals of NAPA, Zerex G-05 and 3 gals of distilled water, plus a thermostat

guy a servcie station where i get my work done, just loosen the lower radiator hose, he said not to open the radiator drain as many times they will not close back and leak or break off.

we drained it and refilled, installed new thermostat, all was good, after i drove it a few miles and warmed up system, then let it cool.

had to add a little to the coolant expansion tank to get back to full

worked fine, old coolant looked good coming out and that is what you want, not dirty crap looking coolant filled with rust particles.

good luck
change coolant at 5years or 100K

 

If you just loosen the radiator drain plug you won't have an issue. Just need a turn or two. The problems come in when it is taken all the way loose. I made that mistake once and it was fun getting it threaded back in the radiator but I managed.