What follows is an interesting comment concerning the heading topic by Maris Dislers on the Barton c/l site.
Was prompted by Brian Winch's latest piece in Airborne, where he runs his long-suffering DC Sabre on a mix of 2 parts Coolpower synthetic oil, 2 parts kero, one part Shellite (light petroleum naphtha) and 1 part nitromethane.
He reported a decent improvement over regular Coolpower/kero/ether mix of equal parts.
I don't have that oil, so used SAE 50 mineral oil. Of course the nitro just sat at the bottom of the measuring cylinder & would not mix. No surprise. No chance to assess the weird concept of nitro in diesel fuel.
Undeterred, I siphoned off the upper oil/kero/Shellite layer and fed it to my Aurora Mills 1.3. In the interests of science and those folk who honestly can't lay their hands on any ether, but must run their diesel.
Needed a wet exhaust prime, but the engine started reasonably easily. I was quite surprised by that, after reading all that stuff about having to pre-heat the cylinder etc. Shellite has a slightly lower auto ignition temperature than kerosene, but still quite a bit higher than ether. Mixture & comp settings are much more critical than normal, but I recorded a fairly decent 7,400 RPM with APC 9x4 prop.
Then added 1% EHN ignition improver, which improved starting & handling. Compression setting back a 1/4 turn, almost to where it runs on regular unnitrated fuel. Recorded a steady 7,600 RPM - nearly 1000 RPM up on unnitrated equal-parts mix. For comparison, this engine turns around 7,800 RPM with a good balanced diesel fuel mix.
Added 10% ether and got around the same as before, but with improved starting & better flexibility. Regular diesel fuel still gives much easier starts and flexibility.
Further experiments aimed at seeing whether Shellite is a useful additive in a regular fuel blend ended when the crankcase cracked at the main bearing housing to sump junction. Certainly when off tune, the etherless stuff burns dirty, suggesting unhappy goings on inside.
Can't be sure that the crankcase was not already weakened by crashes (I've not had it from new), but it's a shame to see it sidelined after my rather good reboring job. Would some kind Aussie with a spare Aurora Mills 1.3 crankcase, for not much dough, come to my rescue ?"