Andy,
Getting back to ether, in particular the JD starting fluid, which JD product do you use ? they list 3 types each with different formulars. The 7oz can is 80% ether with butane and propane and lubricateing oil, the 10oz is listed as haveing 30-60% ether with the bulk remaining being hexhane and 1-10% lubricateing oil.
Now Hexane:- from the wikipedia>:" The straight-chain isomer n-heptane is the zero point of the octane rating scale. It is undesirable in petrol, as it burns explosively, causing engine knocking," - from this we can asume its high on the cetane table.
From reading the MDS sheets for the diferent formulations its clear that different fuel mixes are needed for each especially in the area of ignition improvers, as the starting fluids allready contain these in 1 form or other and at varying ratios.
Stewart