My dad has a 97 S10 with the 4.3. He had a small coolant leak in it and put in a bottle of Bars stop leak a month ago. It didn't really do any good with the leak but he was checking the fluids today and noticed the coolant was quite a bit above normal in the recovery tank. He stuck his finger in it and said it was like engine oil. Then he checked the engine oil and it was about 1 1/2 quarts low. Never used any oil before. No leaks. The engine oil looks clean- no milkshake. Nothing coming out of the exhaust. What could cause this? If it was the headgasket wouldn't it have antifreeze in the oil?

 

Sounds like the oil cooler line inside the radiator has ruptured. Replace the radiator, flush the coolant system well to get rid of the Bars Leak crap.

 

As Rich has stated, if the truck is equiped with an oil cooler inside the radiator (standard on 4wd's IIRC - located in the driver side radiator tank), the cooler could have ruptured allowing oil to leak into the cooling system. This is really the only way that oil could get there and not allow coolant into the oil. The engine lubrication system is typically running at higher pressure than the cooling system.

 

Awesome guys thanks. For some reason I completely forgot about the oil cooler in the radiator. Always thinking the worst I guess lol.