2010 ford f250 6.4, I pulled dpf and installed sct livewire from river city diesel and I am now ready to pull the Egr coolers and install block offs. Apparently I need to drain about 5 gallons of coolant out of the system. Should I go ahead and drain the whole system and put new back in or just replace the 5 gal with new antifreeze? Also should I stick with motorcraft gold coolant? Any recommendations are appreciated😁

 

Drain it all, flush thoroughly, replace with elc and don’t look back.

 

Full flush -- 6.4L (IMHO) is the worst of the 6 series and needs add'l care and attention.

I use CAT ELC coolants in all my diesels --- on and off road. They're designed for significantly more demanding (extreme) environments and have far better properties than the Motorcraft (or any other for that matter) varieties. They also come in "economy sizes" --- barrels.