Graham,,

So many thanks for the wonderful article. It explains a lot about what happened last night. It seems that those that were concerned about the oil settling out were right,, at least partly. Thanks to Global Warming, we in the north have been having truly exceptionally HOT weather this summer. Temperatures have been in the 80s and 90s for three or more weeks. Last evening we had a break, down to a bone chilling mid sixties. Pulled out the old flying jacket and went flying.

Last night EVERYTHING changed. The night I flew the .074 on no ether fuel, was WARM and very windy. After tweaking the top end, I flew at mostly full bore and medium throttle. I recall having a flame out or two but I attributed that to not tweaking the low end sufficiently. I made an ASSumption. Bad science. Last night it was cool and calm and so I settled down to fully adjusting the engine and give the no ether fuel a FULL workout. That's when the fun began. I could easily get a good, strong top end. Power was not up to par but this old .074 was getting on. We all know how anal I am about throttling so I spent a vexing hour trying to get a result that I KNEW this engine was capable of. The idle went extremely rough, occasionally stopped stone cold and it took a full turn 1/4 on the compression screw to smooth things out. But then the top end was overcompressed so I set it at a compromise and went up. I put in one flight that did allow me to idle for as long as I wanted but it was ROUGH with a lot burrp, pop brrrrrr etc. Well, at least it had character.

I had a can of standard mix with me (30/50/20) and so I gave it a try. Everything went good again, top end was stronger, idle and transition came back and I put in a normal flight with full confidence in low level aerobatics. Compression and needles had to be radically adjusted from the no ether mix.

Sitting back contemplating, I noticed my fuel bottle sitting there in the grass and lo and behold NASA, we have SEPARATION. You had to pay attention, but it was there. Worse, as mentioned with the prior freeze test, the separation seemed to show a 40 oil to 60 kero mix. OK, we have an obligation to get to the bottom of this. I went home and transferred the remaining fuel into a glass jar, popped it into the freezer overnight and here we are.

The pics don't show it well but there's obvious separation, no doubt. Interestingly, the dye in the oil, also dyed the kero. OR is this PARTIAL separation with SOME kero in solution with the oil and some oil still in solution with the kero? Probably not, there's a definite line of separation from oil to kero visible.

SO, I flew the .074 with a very high oil content and, relatively, a reasonable kero content. This mix had 2% Amsoil. If the apparent separation reflects the true situation, I may have been getting much higher kero runs at first. As I poured out fuel into my fueller bottle, things got mixed a bit and likely my ratios were not as intended. More kero got in the mix and more oil was left behind till we had NOT our original blend. And this is what we flew last night.

STILL, the engine ran. But here's the rub. As I got home and transfered my no ether mix into the jar, it looked cloudy. This was not noticed in the jug because THAT's translucent. The jar showed this clearly but as I held the jar up to the light, and the mix stirred a bit, it started to clear up. A full shake of the jar produced a clear, fully mixed solution, NO separation visible at ALL and it was also clear. This was in a relatively warm basement so I checked the thermometer and it read 70 degrees plus. So, I left the jar on a top shelf with a bright light and went off to do some puttering. Two hours later, the mix was still clear with NO separation. No mistake, no question. So I popped the jar into the freezer and checked this morning. The result was some serious separation.

I let this sit for an hour and with the jar still quite cold, I gave it a shake. All ingredients went into solution easily. It became cloudy again, so I let it sit for 10 minutes and it was still in solution,,, BUT, here it is, twenty minutes later and we're starting to see SOME separation. This time, the heavier ingredient appears to be predominant but we know these things take time. I'm going to let this solution sit for 12 hours and also warm up to ambient, (about 70) and see what we get.

Bottom line, my ignorance led me to believe that we can run an all kero/castor mix with no problems. Well, maybe we still can. It may be reasonable to assume that we can mix up an all kero/castor mix and as long as we always give the jug a full shake every time we use it, we might have some use for it. The fact that we can store a no ether mix in a plastic jug allows us to monitor its health. Only now, we need to find a CLEAR, plastic jug.

I have to admit that the high ether fuel was a pleasure to go back to. Even with "only" a 30% ether mix, it ran, adjusted easily, and gave me a satisfying flight. But, there's no fun in that, is there? [:@] Maybe the larger engines will respond to a well shaken, no ether mix. That may be the point. Using lots of expensive ether mixes in small engines don't break the bank. Running up to .40's can be expensive. And remember, all of this started with the observation that the Norvel .40 ran well on just 5%. But yes, there were throttling issues and some starting fussiness.

I'm going to let the subject mix sit and warm up for a day or two and see what we get. Then I'm going to add a few drops of ether and repeat the experiment. Just what if that's all it takes.

But something new has appeared on the horizon. Finally, I have some 50 weight, non detergent, aviation oil. Luke Levaseur, local modeller and homebuilt pilot dropped some off yesterday, after stumbling on this thread. Thanks Luke, and now I know where to get it. As "LOU" in the article reveals, and I found out the hard way, castor won't mix with kerosene. Well, not forever. Anyway, it appears that other oils will. Some time back, I bought some soy nut butter and drained off the oil that had settled to the top. This has sat for some months and looks very clear with some gunk at the bottom. The intent was to make up some biodiesel with an unprocessed oil. Kelly has linked me to some excellent articles about how this is done. As it turns out, it's a little more complex than I'm prepared for, so for now, I'm going to do what Lou did, use it as the oil component in a new, no ether mix,,, one that contains varying amounts of Amsoil.

All is not lost though, for a no ether mix. If we can get aviation type, non-detergent oil in THIS small town,,,, I'm sure ANYONE can. And at three dollars a quart, it's cheaper than castor. Hope it works as well. Then there's that Cool Power OIL that Kelly alerted us to.

Castor was the best, so far, in a non ether mix and yes, it'll eventually settle out. Chit, [&o] but it was fun finding out for myself.

Thanks again, Graham. Imagine, this article was written in the 80's. I barely knew diesel's existed back then. []

And Colin, yes, it appears that a warm, kero/castor fuel, well shaken, can be made to work. But you've got to pay attention. [8D]