finally someone also concurs with me,
I have a great example of my moms Honda Accord 1986, travelled 400,000 kms after I rebuilt the engine, still runs perfect, no compression loss, no sludge no noises etc, original Honda radiator, and no exhaust replacement in 10 years - starts up on first crank everytime and runs without complaints - the bonnet is opened once a month to check for oil levels etc.
A Tstat in a diesel is very very necessary - diesels dont like to heat up at all, but need heat to combust fuel spray. they also generate a lot of carbon soot which blackens oil if the piston and rings are not tight (hot) enough
All this is because Ive always used the original T stat in there - it forced the engine to perform at ideal temperature at all times, If you notice in a car - condensation is exhausted out the exhaust when the engine is cold (engine paani maarta hai silencer say) that same condensation also accumulates inside the engine (remove PCV and see the creamy mess) - this condensation which is mixed in the oil eats and corrodes away metal surfaces.
By having your engine at 82C you force the oil to be nearly at 102C - easily steams off water and remains a lubricant rather than abrasive.
Now if this post cannot get you moving to use a Tstat - you obviously love to burn money