It may be possible that your transmission cooler has blown, allowing the two fluids to mix.
Sounds like transmission fluid is getting in to your antifreze. Some types of antifreeze are normally red in color.
Red.
Red,
Red
new answer is basically your head gasket is gone and the oil is mixing with the anti-freeze because anti freeze is not thick and shoud never be thick. The base glycols used to make antifreeze are clear and colorless, the manufacturers dye them to the color that specified by the customer. The color itself means nothing.
Red
Red
Looks like a pinkish red to me.
Gm Dex Cool or equivalent. The red color antifreeze.
Usually it's red, yellow or light green.
red
'DEX COOL' it is red in color.