Gord, good to hear from your advises. I am still little confused with products for the radiator of engine. When I read the Yellow product: Prestone : This says it has a perfect mixing of Refrigerant/Coolant and it withstand a range of temperature from as low as -18 Cent and as high as 128 Cent. The zone where I travel has a range of temperature from around -5 C in night on high mountains close to Lima (very few ocasions) and as high as 35 C (most of time) when I travel on sand deserts along the Peruvian coast hunting for a solitarie and nice beach. Should I mix the Prestone with water (60% of water and 40% of Prestone)or none water and only all Prestone?<P>Graig, good to hear from your references. When I traveled on the Amazon Jungle (temperature is around 34 Centigrated and the weather is very humidy) and the truck didn't have any problems with the engine temperature since the road is generaly flat in spite of the fact of speed and the A/C is on. But by traveling the sand desert, the engine makes a lot more effort specially for a long climbing, specially for a loose sand.<P>Rodolfo