I have a 1998 Chevy half ton pick up with a vortec 305 5.0 liter and recently did a radiator flush because I thought that the cheaper non ac delco coolant i had put in prior had become bad and turned brownish. It looked all black and smelled almost burnt. so i did a radiator flush. a couple of months later i changed my oil and it was a couple of quarts short when i took it out and the coolant again was dark in color. any idea what would be causing this? My coolant level isn't high so i don't know what would cause this. Any ideas? By chance could the detergent i used to flush the radiator not have done a good job?

Ideas would be greatly apreciated!
Ryan

 

Sounds from your description that there might be oil getting into your coolant. Any overheating problems? Does the coolant feel oily? Any white looking stuff in the radiator?