Transmission fluid change @118kmiles change @own risk

[omodos]

Hello all, this follows on from my trans.failsafe.prog message that hasn't appeared in 200 miles yet after codes reset by 1st mechanic.

I have been told by 2 mechanics now seeing as the 'life-long' fluid has never been changed (yup fell for that one by BMW my fault) changing transmission oil/filter now at 118k miles is at my own risk...one actually said 30% chance will remedy issue other wasn't that specific.

This follows on from TCM check showing the temp of the trans oil hits 100c, over the span of 40mins. It didn't exceed this temp, but mechanic adamant its because ambient temps are about 20c now, once we hit the 30-40c summer time then and it MAY go over 100c then I will have issues

What frustrating is that the underbelly 'shield' concealing the transmission hasn't been removed to check if there is a leak, if there is a leak its a no brainer.

In case there is a leak then well the service kit is needed with filter and the mechatronic seal etc correct?

If there is no leak and the fluid has deteriorated, is it less risky at my mileage just to replace as much of the existing transmission fluid with fresh, rather than doing above?

I am basically rather stuck now...damned if i do damned if i don't , if I had any of the diag tools mechanics used to monitor trans temp then i would be tempted to wait and monitor and see, but am a total newbee to any tool, if anyone has any link to software that can be used on a laptop and what type of connector is needed be much appreciated.

In the meantime as mentioned there was a turbo hose cracked that was remedied

We are doing a full coolant flush and oil change can't do any harm (does the transmission oil actually get cooled by general coolant system?)

And to top all this off for the life of me try and try again to create trans.prog issue I could not, the same steep hill I drove down in the past which 'created' issue I hit 4 times over and over and the message just didn't appear ...