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fuel mixes for nitro engines

Old 02-21-2016, 06:59 PM
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multimike
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Default fuel mixes for nitro engines

OK I am confused, I have been in this hobby for over 60 years and I always thought we use castor oil because it was vegetable oil and oiled and oiled the engines so the guys got into a discussion about synthetic oil which is now used in our fuel so is it a mineral oil ? we cooked a couple of engines by having a bit of a lean run, so we put some mineral based oil into some methyl and it would not mix !! We use 15% Cool Power that has only synthetic any info would be much appreciated Mike
Old 02-21-2016, 07:28 PM
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jester_s1
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There is a very wide range of oils that fit under vegetable oil, mineral oil, etc. Castor just happens to have the right mix of properties that make it useful in our engines.
Old 02-21-2016, 09:22 PM
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speedracerntrixie
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Mike, the real issue is the way you are tuning your engines. No oil package will protect your engine from premature wear if you constantly run them lean.
Old 02-21-2016, 09:38 PM
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My limited knowledge / experience of oil contents in different fuels - definitely depends on what materials your engine is made from, how wear resistant it is, how it is designed. Iron vs steel pistons/sleeves/cylinders, etc. Since getting back in the hobby about 2 years ago, I have been awed by the sheer tenacity of castor oil. It simply does not break down, getting spit out the exhaust about how it went in. I am pretty awed by this comound being produced naturally in nature. I don't think the petroleum based lubricants are as thick (viscous) and perhaps cannot stand up to the heat / oxidation of combustion. The high viscosity may create drag on the engine to limit RPM's (?) Living near Old Rhinebeck Aerodrome, it has been on my mind to ask about what fuel recipe they are using for their radials / rotaries up there. Wondering if they go through gobs of castor oil or if they use synth / modern compounds.
Old 02-22-2016, 09:05 AM
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JollyPopper
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I am not a chemical engineer, so I can only rely on what I have read about these kinds of things and I have read that castor tolerates heat much better than synthetic. It continues to protect long after synthetic has broken down and quit working. So the bottom line is that if you have a tendency to run engines lean or if that happens accidently, castor protects when synthetics don't.

But, even if castor didn't have these advantages, I would continue to use it because it smells so good coming out of the exhaust pipe of an engine. I try to buy only fuel that has at least 50% castor in the oil content, and if it doesn't, I simply add about four ounces of castor to the jug.
Old 02-22-2016, 11:56 AM
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I thought it was only the heli guys debating oil type and content in glow fuel

Yep, castor makes for better heat protection, synthetic makes less of a mess and leaves a nice protective coating after running versus the congealed mess you will have if castor fuel isn't cleaned out of a stored engine
Old 02-23-2016, 04:57 PM
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MJD
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Originally Posted by BrightGarden View Post
My limited knowledge / experience of oil contents in different fuels - definitely depends on what materials your engine is made from, how wear resistant it is, how it is designed. Iron vs steel pistons/sleeves/cylinders, etc. Since getting back in the hobby about 2 years ago, I have been awed by the sheer tenacity of castor oil. It simply does not break down, getting spit out the exhaust about how it went in. I am pretty awed by this comound being produced naturally in nature. I don't think the petroleum based lubricants are as thick (viscous) and perhaps cannot stand up to the heat / oxidation of combustion. The high viscosity may create drag on the engine to limit RPM's (?) Living near Old Rhinebeck Aerodrome, it has been on my mind to ask about what fuel recipe they are using for their radials / rotaries up there. Wondering if they go through gobs of castor oil or if they use synth / modern compounds.
They definitely use castor oil, at least in some of them.
Old 02-25-2016, 12:53 PM
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mscic-RCU
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Originally Posted by multimike View Post
OK I am confused, I have been in this hobby for over 60 years and I always thought we use castor oil because it was vegetable oil and oiled and oiled the engines so the guys got into a discussion about synthetic oil which is now used in our fuel so is it a mineral oil ? we cooked a couple of engines by having a bit of a lean run, so we put some mineral based oil into some methyl and it would not mix !! We use 15% Cool Power that has only synthetic any info would be much appreciated Mike
I have never liked cool power because I thought it was a little light in the amount of oil. OS recommends 20% to 22% oil content (http://www.osengines.com/faq/faq-q663.html) and Saito recommends 20% oil content (http://saito-engines.info/fuel.html). I like a blended fuel between castor and synthetic, but synthetic keeps your engine cleaner. IMHO, it is not necessarily the kind of oil but the amount of oil in the fuel.
Old 02-25-2016, 02:34 PM
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Byron Rotor Rage solved me changing bearings twice a season in my heli engines. After that it was once every 2 or 3 years. Note I live in Florida so thats a LOT of flying.

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