I read on this forum that the redline "red" water wetter separates in antifreeze....but re-mixes when warm. The "red" redline water wetter is designed for a water only application in gasoline engines, and as such contains some additives that antifreeze would have...but still keeps within the racing regulations? The suggestion was to use the "purple" redline water wetter for diesel engines. This does not have the additives that separate out. Again, I am only repeating what was mentioned in a post that I read a while back.