If you decide to switch to an ELC style coolant, first of all, not just ANY ELC will do. It must have the CAT EC-1 rating.
There is a Shell Rotella ELC that meets that rating that is supposed to be "the best," but any CAT EC-1 rated ELC will work. International Truck dealerships carry the Fleetrite ELC which is CAT EC-1 rated and what they installed in the VT365 (International variant of this engine) from the factory. NAPA also sells a ZEREX ELC that meets the CAT EC-1 rating.
A few things to keep in mind:
One is that you need to purchase the CONCENTRATED form of the ELC, since the cooling system retains approx 50% of the total capacity when drained during your flushes. If you were to buy the premixed, you will never get to a 50/50 mix of coolant and distilled water.
Then next thing to be aware of is that you can not just drain out the Ford gold, flush only with distilled water and think everything will be ok. You are changing the coolant type, not just the coolant. To change coolant type REQUIRES that you flush using two chemicals. The restore and restore+ flushes serve two different purposes.
The restore chemical flush removes a film that the Ford Gold coolant deposits on the walls of the cooling system to help combat cavitation.
The second chemical, restore+ (same as the ford VC-9, only less expensive) is to remove rust scale build up in the cooling system. If the dealership used tap water (and I will bet you they did) you will have rust scale.
Should you skip the restore step, you could have a chemical reaction between the film left by the Ford Gold and the ELC style coolant. If you were to skip the restore+ step, you would be leaving the junk that clogs the oil cooler sitting there as a ticking time bomb.
Here is the flush i did used 48 gallons of distilled water 1/4 tank of fuel and 12.5hrs of my time BUT my cooling system is clean.
This should help you understand the reason to ditch the Gold junk it can't take the heat. Gauges are a must to do this need to know EOT-ECT
Replaced oil cooler still difference in temps
Flushing and cleaning the 6.0
Restore is for cleaning out any silicate goo. VC-9 is for cleaning out iron and scale. Restore Plus is the same as VC-9 and cheaper.
To flush drain the coolant by removing the lower radiator hose from the radiator, and removing the drain plug from the driver side of the block. There is a drain plug on the passenger side also but you have to remove the starter to get to it. I don't bother with that one.
I also highly recommend you pull the thermostat out on your first drain and put the housing back without the thermostat. It only takes about 10 minutes and will save you 2.5 hrs or so in doing this whole procedure.
Ok now put the lower hose back on and the drain plug back in the block if you removed it. This is the procedure you will use each time to drain the system, except you will not touch the thermostat again until you're finished the whole procedure. Make sure that you set your heater to high while doing this to flush out the heater core as well.
Fill the cooling system with distilled water, start the truck and let the water circulate for 5 minutes. (if you did not remove the thermostat you must run the truck until the thermostat opens + 5 minutes to circulate. This takes 15 to 20 minutes each cycle and is why you should just remove the thermostat) Stop the engine. Drain the system and repeat the flush.
Now add at least 1/2 gallon of Restore and fill with distilled water. I used cardboard in front of the radiator because you have to get to 185* 190* for these products to work. Drive truck or run on high idle for 60-90 minutes just before you get back from your drive remove the cardboard this will help in the cool down same on the Restore+ flush. Drain and flush 3 or 4 times. or tell clean
Add 2qts VC-9 or 1/2gal of Restore Plus, top with distilled water, and drive the truck or run on high idle for 60-90 minutes. Now drain and flush until flush water comes out clear and clean. When you get clean flush water, flush 3 more times using distilled water while draining the block.
After your final distilled water drain it is time to put the thermostat back in. I recommend you install a new thermostat at this point. They are only $20 or so and it is good maintenance procedure to do so. Fill with 3.5 or 4 gals of ELC concentrated coolant and top off with distilled water. Drive the truck or let run for a while topping off with distilled water. Check the truck over the next few days and top up as required while any air left in the system works its way out.
Keep some 50/50 ELC on hand to use to top off the cooling system from here out and you are good to go.
new t/stat from Ford it should all come together (housing-t/stat-o-ring) in a box. The part number is RT-1169
Here is the Restore Product from Cummins dealer