I just purchased a 1998 SS with a 5.7L LS1. There is oil in the coolant, but no signs of coolant in the oil - (no milkyness on the oil filler cap even). My question is: is there a possibility that the oil cooler is leaking oil into the coolant? If there is no possibility of being a problem with the oil cooler, is there any other known issue that could be causing it? I have not tried flushing the system yet to see if someone accidently put oil in the coolant tank. The oil in the radiator is also in the reservoir and is definitely brownish, not reddish, so I do not think is from the transmission or steering coolers. I am planning on changing the radiator because this one has a small crack, so I would like to address the oil issue at the same time. Any help would be greatly appreciated!