After replacing the heater control valve today, I flushed my cooling system and heater core out. I am now using Chevron DELO EC1 pre-mixed coolant. This coolant is used in Big Rigs and has a 600,000mi or 12,000hour life span. It is recommended for aluminum engines also. I bought it at a petroleum distributor. It is a 50/50 mix with de-ionized water pre packaged. It is approved by ALL of the major engine companies...Caterpilar, Navistar, Cummins, Mack, Detroit Diesel, Ford, and GM. It has a temperature span of -34 to +265 degees F with a 15lb cap. The price is reasonable at $7.50 a gallon for the pre-mix. They also sell a concentrate to mix 50/50 but it wasn't much cheaper once you figured it out.

__________________
My Truck.. 2007 DODGE, 5.9 Cummins, 6spd stick, 4X4. My car..1977 240D, OTHER WHEELS...1955 VW Oval window bug, European Delivery (Holland) with a 1700cc, 2 barrel, Porsche drum brakes. 1939 WILLYS Pick-up. 1967 Triumph 200cc Tiger Cub. 1976 Honda 550F 4cyl Motor Cycle.