Thermal buffer: avoid surface evaporation of hot water with oil or other blocking product?

[Christophe]

Have you studied the trail of the small polystyrene balls that float on the surface?

Yes and it's crap! See above !

[Christophe]

Here is the state of the bottles after 7 months...

The indicator and the balls are completely empty, there remains a background of iso46 (more water)...the ATF and gearbox oil are at the same level, around 150 g and the 5W40 and LHM at around 190 g. .. (it rained inside in a not necessarily equivalent way...)

All are "moldy" and more or less diluted in water (but there was external contamination that there would not necessarily be in a closed space and without light):

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[Christophe]

I will carry out the 2nd stage of the experiment: the same thing with LHM in an opaque container, closed (therefore without contamination) but breathable (that the humidity passes the lid)...

I'm going to put in my greenhouse so that it heats well!

[Christophe]

A year later, I confirm that the LHM is THE PRODUCT to block evaporation...

The bottles are still outside and 0.0% evaporation in the LHM bottle...all other products have had losses...some are completely empty...

It now remains to check the durability and chemical compatibility of the LHM with a possible tank (in metal or plastic, no worries...I assume but my tank is concrete tubed...)...not yet done despite my previous message ...

[Macro]

Remain especially in your case to manage to support the smell of this filth...

[Remundo]

kézaco already the LHM?

[Macro]

"citroen" mineral hydraulic fluid

But if he wants I better question degeulasserie dsg gearbox oil ... a treat

[Remundo]

ah yes going back the pages, I saw a pdf

they are hydrophobic petroleum products which evaporate little.

but obviously it's oily and quite "chemical"...

Lubricating oil (petroleum)
C15-30

in cold weather it should even freeze...

but to isolate the water from the air, that is what is needed.

it is not necessarily toxic; very little volatile and stable in stagnant water, except of course to eat it.

[Macro]

It does not freeze in the cold... Otherwise the ds, cx, gs, bx, xm, xantia c5... Would have remained on the ground in the middle of winter...

[Remundo]

yeah okay Macro, but the doc talks about oil from C15 to C30 in the carbon chain

http://www.atomer.fr/1/1_alcanes-lineaires.html

pentadecane melts at 10°C

so I don't have the precise answer, but C30 alkanes normally freeze at room temperature.

after when there are mixtures, branched alkanes and other "melting"...

actually we can think that it does not freeze since it is used in cars.