hello

I have just gotten an 87 745t with 286k.
right after i got it i switched to mobil 1 5w30 oil and drained the oil cooler to make the switch.
but now the oil cooler will not heat up after driving any amount of time the cooler is cold to the touch.

Is this normal?

I am starting to hear an either scraping/swoshing sound coming from the passenger side when the turbo boost is at 10 and goes away after positive pressure but is most noticable when i let go off the gas, that makes me think it's a vacum leak but i dunno also de turbo boost will never go past 3 o'clock.

I guess my question is did i have to prime the oil cooler full of oil before getting started after a drain.
I've only had a 740n/a so far and the turbo is new to me

Any insight would be great.

Thank you
all the best

As John pointed out the cooler has a bypass thermostat that opens at 95C or around 200F and below that it completly bypasses the cooler stage so the oil can at least get warm enough to drive the moisture out, during the winter it would not be very good to have the oil running at say 50F all the time being cooled by cold air and the net result would be lots of sludge.
Your switch to mobile-1 is a good move in itself so I wouldnt worry about it at all.

The whoosh sounds like a leak on the pressure side or maybe the wastegate is frozen up in the open position however I doubt that. Look to see if any of the couplings between the pipes has broken loose, it doesn't take much of a leak to drop the boost way down.

Badge988

The oil cooler adapter has a thermostat in it that does not open until 95º Centigrade. Unless it is hot outside, and you are running the car hard, no oil will flow through the oil cooler.
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john