My 03' Cobra has the Green Coolant in it. Don't know if it's the Factory Ford stuff or not. I'm gonna be doing a FULL Coolant Service to both my Engine and Intercooler Coolant Systems. The Owners Manual and a lot of other areas say to ONLY use the Factory Ford stuff. Is that because they don't want to chance mixing with anything else? Or is it also because of the quality/chemical make ups? So my question is, why can't I just completely drain/flush BOTH systems out and refill using some regular Prestone Coolant?? Do I really have to buy the FORD Coolant? I don't see why it would matter as long as I emptied ALL of the old stuff and put 100% of the new stuff in. Also I have like 5 Gallons of Prestone and it says use only in 2001 or Older Fords. Would it hurt to use that?? Any info would be appreciated. Thanks guys