Yeah, lots of things are COMMONLY known, and are not true. And as I have said, I have heard that about just about every fuel, from people who fly a different fuel. So if ALL the reports are true, ALL fuel manufacturers do that. Oops, I don't think I have ever heard anyone acuse SIG of this. 
Has anyone TESTED the various brands of fuel?
Very extensively. I've done a bunch, and I know Randy Smith has done a lot more. I am sure everyone has gone through fuel testing on some level at some point. BTW, the evaporation test takes too long - you need to boil it off.
My results were that, for the most part, the fuel manufacturers were telling the truth on the total oil content. Byron "16%" oil fuel had about 15.xx % oil by volume, Byron "20%" oil fuel had 19.xx or so%, SIG had about 19%, etc. Omega has about 15%, Cool Power has about 13-14%.
No matter what R/C geniuses (aka sport fliers with ~6 months of experience) tell you, for stunt flying I would be hesitant to go below about 18% unless you really know what you are doing and are willing to pay the potential price. For slug-piston engines, I wouldn't use any less than 25% straight castor, and more certainly doesn't hurt anything. For ringed engines I would use 18-22% castor/synthetic blends. Not all castor - you need at least some synthetic, and I think at least some castor.
For AAB/ABC engines I have no particular problem with the idea of running straight synthetic, and will admit to using as little as 16% on super-high-quality AAC engines. Right now, I run Powermaster 18% oil fuel (in either 10 or 15% nitro) which has a 75/25 synthetic/castor blend. Regular SIG Champion is about the same +-. I think, however, that there is a definite possibility of varnishing that messes up the fit. Richard Oliver has in the past suggested that the low-viscosity helicopter oil is the way to go, but there appears to have been some recent problems with some sort of deposition with that. I have in the past run YS 20/20 in AAC 2-strokes with excellent results, and I plan on running it occasionally to clean the varnish.
Oil drag and varnishing is a very real problem and power-sucker on the very tightly-fit AAC motors, and I think the oil drag tends to make the 4-2 breaks or other power shifts much more sluggish - I don't really understand why. Maybe the oil drag in the front end does it, I think that the front end needs to run pretty free. It's probably even worse in our low-output, cold, stunt settings.
As far as brands go, I like and have had excellent results from SIG, Powermaster, and the much-maligned Byron "Classic". The only thing that I have found wrong with Byron is that the performance is weak for a particular stated nitro content. 10% SIG is stronger than 15% Byron. If you choose sufficient nitro for the desired performance, I have found Byron to run noticeably smoother than the others, with a very "smooooth" power transitions. And in many cases, Byron would solve the "flameout" issue when no other fuel would. SIG tends to be noticably stronger for a stated nitro content, and Powermaster is somewhere in the middle, but not a lot different from SIG. SIG, in some engines (we noticed it first in the PA61, but only particular examples, not all of them) tends to form plug "taters" that make the plugs last as little as 30-40 flights. I can only speculate as to the cause, but it sure looks like some sort of polymer and the best guess is that is has something to do with the anti-foaming agent. My buddies and I switched to Powermaster and now it doesn't happen to any significant degree. If I couldn't get Powermaster for some reason, I wouldn't hesitate to switch back to SIG and wouldn't worry about it.
Cool Power, Omega? If you add a lot of oil and/or don't care much about the long-term durability, you sure aren't going to have any oil-drag problems. They have a bad reputation in stunt for a very good reason. I have had sporadic problems with SIG and Powermaster, but out of the dozens of cases of fuel I have run - through only maybe 4 individual engines - they were few and far between. Cool Power and Omega are pretty notorious - if that's all you can get, use Omega and add about 8 oz of castor per gallon, and cross your fingers.
I also had excellent results with Red Max back in the late-80s/Early 90s. Along about 1995, they were responsible for starting the "castor oil is bad" rumor. Since this was about the same time as the "1995 SIG Disaster NATs", where some clearly bad fuel from SIG wrecked more than a few stunt engines, it actually seemed true. However, SIG quickly diagnosed and corrected the problem, and Red Max went off on a tangent telling everyone that it is not possible to get "good" castor any more for anyone, so use our "Mystery Super Oil" instead, it works great in go-karts. After going round and round, including several of us calling them directly and talking to their "oil experts" I came to find that the only problem appeared to be that *they* managed to buy a bad batch of castor (which contained, among other things, xylene, which caused some sort of precipitate to form). Well, that wasn't the only problem, they also knew for certain that we (C/L pilots) were really not too bright and should go talk to some R/C guys, since they were so advanced. I hear then even did that with a certain 5-time National Champion. After that, I simply wouldn't do business with them any more. The same story appeared on their websites until very recently, with a variety of ever-more-creative excuses for their castor and how great their magic oil was, when AOL shut down the free hosting. Mercifully, their new website contains none of this garbage, but they certainly aren't getting any of my hard-earned money. The whole story is on SSW in several different versions.
There seems to be more arguments, and heated arguments, over oil and oil content than anything. After going round and round, and running more fuel that most ever will, I just get the quality fuels from reputable manufacturers, and don't really think about it any more. Compared to everything else, the fuel is dirt cheap even with hazmat shipping. I use, at most, maybe 10 gallons a year at this point, maybe a total of about $250. I spent much more than that just for a hotel for the SWR a few weeks ago. Fuel costs are in the noise compared to everything else, don't try to save a few dollars a gallon.
Brett
p.s. this is pretty much all you ever need to know about the topic, and might save you a lot of pain:
http://stunthanger.com/smf/index.php?topic=4037.0 Randy knows as much about the topic as anyone, take advantage of his hard-earned knowledge.
Topic: FUEL TYPE (Read 8632 times)