Part of ether dissolves into the oil, and likely also into part of the kerosene: the resulting
volume is less than it would otherwise be. The fraction of ether dissolves like salt or sugar would in water,
into the water without changing the volume? ...until saturation, of course, after which further added volume becomes evident? (Not voicing doubt, just clarifying whether I understand.)
I infer that a high precision
weight scale should then show the full weight of the ether added? (And I ain't got one of those, either.
)
What I said was that the Ether dissolves part of the oil. The Ether is a
strong solvent, the castor oil is the solute. The Ether
may dissolve part of the Kero. It is most noticeable with the Castor. Just about everything dissolves and/or mixes in Ether. Notice that Castor and Kero don't normally mix very well? Add Ether and they do.
I would expect that an accurate "weighing" of the components and the combined mix would show no loss of Mass.
Do commercial model diesel fuel makers blend %s by weight or by end volume? I know most, if not all, USA glow fuel sellers mix components by volume, and I recall no comments about any volume loss with fractions added to reach end volume. Perhaps the methanol, nitromethane and 'castor/or synthetic/or both' fractions don't inter-dissolve?
Were volume loss as large as you indicate with ether/oil and ether/kerosene, I expect glow fuel buyers would complain of being shorted on the nominal volume of their purchase. Practically ALL fuel here is sold is in translucent, I think the term is HDPE, jugs or bottles - such loss would be quite evident.
I have not bought pre-mixed diesel fuel since the 1960's. It's simply not available. I mix my own, only in one Litre batches as I need it..
In glow fuel, the Methanol is the Solvent. It is not a strong solvent like Ether. There probably is some slight castor oil volume loss, but I've never noticed it mixing only a Litre at a time.
I'd imagine that commercial fuel mixers would do so in a quite large container. Large volumes are notoriously difficult to accurately measure, while large quantities of liquids can be weighed using large commercial scales. The Density of Ether, Castor and Kero individually are easy to determine. A one time calculation is all that's needed to get the right Masses for the correct Volume proportions. They can then be mixed in a large container and decanted into the HTPE jugs or bottles of the required volume.
Separate thought specifically re: diesel blends. Most 'home-brewer' comments seem to mention frequent starting problems compared to commercial fuels. After suggesting making sure of the quality of the kero and the oil, the usual suggestion is to add more ether, right? What disadvantage would adding ether to reach the co-dissolved end volume have, other than the cost of the ether?
I'd suggest that notion that diesel starting problems due to Ether loss in stored fuel is more of an internet meme than a real problem. I'm a long time model diesel user in a modelling culture where diesels are in constant use. Summer temperatures can reach the mid 40's Celsius. People mix and use the fuel in small quantities. It's simply not an issue.
What is the consequence of mixing homebrew diesel fuel in such a way that there's extra Ether. Only that you're not using the proportions suggested by the manufacturer. A brew with a real content of 32% rather than 30% Ether may actually improve starting.