I have a 97 S10 ZR2 with 104000K on it, and a 5 speed Transmission. Today I decided to do the oil change, a little early Mileage wise. After the oil change, I check all the fluid levels and noticed that the coolant in the radiator overflow tank appeared brown in color. When I opened it up, it looked and smelled like oil sludge. I removed the radiator cap and the Dex-Cool look very brown, but it still had that familiar DEX-COOL liquid texture to it. The truck has a oil cooler but I didn't notice anything different with the old oil, such as coolant in the oil, when I changed it. I change the water pump last summer and I put fresh coolant in then. I am going have the radiator flushed tomorrow or the next day, but I am a little concerned about it since I have never seen this before. I know that oil coolers and trans cooler can cause this but I have a manual trans and the oil cooler appeares to be fine since no coolant was found in the oil. Any help with this problem would be greatly appreciated.
Thanks
Mike