Oil Contamination in Coolant Reservoir A Mechanic's Perspective

basically what the TSB says is that "there was an internal casting issue with the block at the cylider walls that would allow the oil and ... The black gunk in your overflow reservoir looks kinda like misshapen globs like what you see in a lava lamp, it may be engine oil. Blown head gasket\cracked head if you're not getting a CEL with a miss. Oil and coolant only combine into that nice brown goo under high ... If you have OIL in your cooling system they had better be replacing the oil cooler. It is not uncommon for us to replace both the oil cooler and ... ... oil is getting in your coolant overflow tank. Oil coolers and transmission coolers are very comment causes of oil in the coolant so you want ... Transmission fluid would be physically impossible. It has to be engine oil. Oil cooler replacement is the #1 suspect given the timing. The only good news is that oil in the coolant is better than coolant in the oil... Expensive fix, but probably worth doing. Any car can have a head gasket fail. You should be able to see the colour of your antifreeze in the reservoir tank when you remove the radiator or coolant reservoir lid. Oil remnants will be seen ... The problem, in general, is that there is a leak between the lubrication system and the cooling system. There are only few obvious where this can happen. 3G TL Problems & Fixes - Oil in coolant reservoir and radiator - This is for my uncle's TL-S. It's a 2007 Automatic.