I have a 2005 S60 Volvo and and I have peanut butter oil however I would like to find out possibly where the leak is internally because I do not have an external leak there is no oil leaking from this vehicle. After doing some research I found online that the oil cooler may be the culprit are there any suggestions real suggestions not the obvious suggestions as I'm not an expert however I'm also not a novelist. If the oil coolant is not the culprit of the internal leak of coolant to oil or oil to coolant then I'm fine with just moving on from there thanks for reading and Responding objectively Thanks

 

Do you have any oil in your coolant? Have you done a head gasket test (there's a kit to test HCs in your coolant - which happens when the head gasket lets exhaust gases into the cooling system). It is possible that the oil cooler is leaking coolant in but its also possibly a head gasket so you need some more investigating...