Makes perfect sense why it's not happy in some sorts of oils now...
Thanks Mike, really appreciate you posting the above

white exec wrote: 30 Nov 2017, 10:54 The lower reading when hot has been like that since new. When cold, gauge can read Full; after driving and re-starting, reading is pretty variable - usually about half or a third. It is responsive to oil level though.
What you say about before-and-after measurements makes sense.
The sensor must get pretty hot to still be able to make its heat-loss calculation in scaldingly hot engine oil.