Q – For about three weeks my 1987 944s has been losing coolant but I cannot find a leak. Now I began to notice that my oil is looking odd like a chocolate milk shake. The car runs fine and it has never overheated. Any ideas? Bill
A – On the 944 there is an oil cooler mounted on the passengers side of the engine block and by now, most of them have baked seals inside that one cannot see from the outside. Stop driving the car and have a sample of the oil taken and sent to the lab to detect the presence of coolant. If the test comes back positive for coolant, have the oil cooler resealed and while it is off the car, have the cooler pressure tested. I have only seen one cooler actually fail but I have serviced dozens of coolers with failed seals. By this time in life, any 944 owner should consider it a by product of age and heating/cooling cycles and therefore include it in a maintenance program.
As far as the oily milk shake, once the cooler is resealed, drain the oil, add five quarts of cheap oil, install a new filter, let the car warm up for about 15 minutes at idle, add engine flush (follow the instructions) then drain it and do a proper synthetic oil change .
Caution: The oil cooler is not the only possible cause of coolant in the oil. It is just one of many…and the most likely cause. Had you ever had an overheat, I would suspect a head gasket and on almost any other car, the head gasket would be the most common failing part due to an overheat. MC