I am in the middle of replacing my Upper Radiator hose (X-type 2002), when I got stuck trying to remove the 13mm nut for the thermostat housing, it is in an awkward position. and I can't seem to get it out. Are there any tricks or tips on removing it?

 

I just changed mine. Ended up using a combination of tools to do the job.

The end result was that a 3 inch extension and a thin wall socket was needed for the one that's impossible to touch.

Once loose, I used just the extension and socket between my fingers to unscrew it.