If the stuff in your coolant is a reddish "strawberry milkshake" type goo, STOP DRIVNG IT. When I had the same problem on a different type vehicle, the transmission oil cooler inside the radiator had failed, and I was cross-contaminating the coolant and transmission fluid.
The fix was a new radiator, but the 'collateral damage' included a transmission rebuild, new water pump, hoses and a lot of flushing and swearing.
The heater core went about a year later, but I'm not sure it wasn't related.
If lucky, the tranny would only need to be flushed aside from the radiator replacement and cooling system flush.
Just a warning of a possible situation that should be checked out.
Scott