DHD always recommends using quality AcDelco fluids in your Duramax. Don't be fooled by one type fits all fluids!
ACDelco Dex-Cool 50/50 Premix Coolant/Antifreeze is an orange, silicate and phosphate free, premium-grade coolant with a chemical composition that reduces breakdown of metal components in contact with the fluid. Based on carboxylate technology, ACDelco Dex-Cool 50/50 Premix Coolant/Antifreeze has the properties needed to optimize the efficiencies of the new hybrid vehicles. This product is acceptable for use in all vehicles that require Dex-Cool coolant. Perfect for on the go situations, ACDelco Dex-Cool 50/50 Premix Coolant/Antifreeze comes pre-diluted with specially filtered water and is ready for instant use.