[drover]

If your cooler has let go and the system has had oil thru it all the hoses are probably rotten by now or close to it, may be shedding particles, the radiator really need to come out and get a decent flush as well, the oil will hang in the galleries forever, its not just a radiator reverse flush job ........ these can be a pain in the arse to fill with coolant as well... coolant should be a nice red colour in header tank with no goobers in it, though you may get some gunge from the oil dump .

My coolant temp with normal driving sits around the 95-101c mark when dragging the rig behind (2.8t) much the same, only ever see 120 when Im really working it hard dragging van up some monster hill ......... oil temps normal runs is in the 98-102 mark and 105-8 area when dragging the rig, when they do climb up they drop back quickly as the load drops off.

There was a TSB a long, long time ago about fans going crazy but with an oil temp of 120c it could be why it fire up on high .....................

If you have Alfa OBD app you can turn on SRT gauges and get a coolant temp and oil pressure on the screen, very handy.