I have a 2000 F-150 4X4 with a 5.4L and auto trans. and 222k miles. About 18 months ago I had to replace the radiator with an aftermarket. About 6 months ago I started smelling coolant in front of my truck, brought it to the dealer and was informed it was leaking at the lower right corner. The place the dealer bought the radiator from repaired it for free and then I was told by the dealers parts dept. I should be using "distilled water" in the radiator! The service dept. tells me that's hogwash. Now my radiator is leaking again. I was in the service end of dealerships for the better part of 25 years and have never heard of using distilled water in a radiator. Has anyone experienced this? Is it true? Not?

 

I have never used anything but distiller water in every single vehicle I've ever owne. No minerals or anything to deposit/build up in your system. Too much variance and too much stuff in tap water. Yes, this is very true...or at least I've always heard it, always been taught that way, and always done it. Wither you agree or disagree with this practice and the reasoning, one things for certain...using distilled water isn't gonna hurt anything. It can only help.

 

I have never USED distilled water in a radiator. Quality brands of coolant have sufficient additives to prevent corrosion if you change it at least every 3 years.