Sent 2 prev. questions re "oil" in overflow tank. Rec. 2 replies.

The only way you are going to "get a solid answer " is through hands-on testing by a qualified mechanic! .. The transmission cooler inside the radiator can easily be tested by using controlled air pressure to check for leaks .. The 3.1L pushrod engine simply is NOT subject to injecting engine oil into the cooling system as there is no oil that's under pressure flowing by the coolant passages .. Your best bet is to have a *qualified mechanic* check this out for you hands-on .. Suggest you check the engine oil and the transmission fluid for any signs of coolant mixed in with either of them as the residual cooling system pressure will in turn force coolant back into the source of whatever is in the coolant overflow tank .. That's about all the help we can offer over the internet .. Good luck with it!