I've flown RC for a long time & as you know, building a similar 5-cylinder glow radial. For sure I plan on buying RC fuel for the radial because there are no advantages I can think of mixing your own, but some potential disadvantages. I would recommend selecting a reputable brand from your hobby shop at least for the first quart or gallon & ease into it, so you have eliminated an variation there's. For example Powermaster or Morgan fuels (I might be dating myself). They offer gradations of oil & nitro content. But there are other goodies in there that you would be guessing at - stabilizers, anti-foam, ingredients that help castor & synthetic get along. The only difference to the Edwards from what commercial RC 4-stroke fuel would be is you are potentially introducing a tiny bit of lubrication oil into the mix via the Edwards lubrication system. But whether that translates into a net increase of oil% in what becomes your combustion mix is debatable IMO. But you do want compatibility so that the lubrication oil doesn't go funky. That's likely why Edwards recommended castor, but fuels have evolved since then too. Slightly higher oil content wont really hurt anything (within limits). Lean oil content is the bigger worry, heat & seizure is usually not far behind.
Methanol is sold by grades of purity & engine running is sensitive to it, so you need to be sure what you are getting in the custom blend world. Even otherwise good commercial fuel can go bad over time in partial/opened containers in humid conditions. Increased nitromethane content as a general rule may help your starting, idle & transition. But there many other variables involved (glow plug heat type, compression, break in condition etc.). Some castor oil content within an otherwise synthetic oil based fuel is very common in commercial fuels, even among the best fuels for demanding applications. Pure castor (only) has fallen out of favor for reasons mentioned. Its a bit messy & can varnish more-so than synthetic. Some of the fuel blenders sell their (premix) oil separately so you could go that way with the circulating lubrication system IMO.
What is probably THE most important thing for glow engines is maintenance ritual. If the engine is going to be parked for a couple of months, best to remove the plugs & partial disassemble to the extent you can flood the internals liberally with a good quality oil so that the important surfaces are all coated. I just store engines this way in a ziplock bag. When it comes time to run, drain this oil out, flush with a bit of fuel & ready to go again. RC after run oil is sold for this purpose but like most things, opinions vary. Some blend their own. Some from the high performance community advocate pneumatic tool oil for this purpose. I've used both successfully. The key thing is it coats & protects from corrosion in the down time & must flush away with no real residue or compatibility issues. I'm leary of people who use gear oil or ATF oil because some of those blends don't play well with brass & bronze (of which we have several parts in the radial). Other considerations like silicon O-rings, seals, synthetic gaskets are sensitive to certain ingredients. I steer away from WD-40 for this & other reasons.
Hope this helps!
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Methanol is sold by grades of purity & engine running is sensitive to it, so you need to be sure what you are getting in the custom blend world. Even otherwise good commercial fuel can go bad over time in partial/opened containers in humid conditions. Increased nitromethane content as a general rule may help your starting, idle & transition. But there many other variables involved (glow plug heat type, compression, break in condition etc.). Some castor oil content within an otherwise synthetic oil based fuel is very common in commercial fuels, even among the best fuels for demanding applications. Pure castor (only) has fallen out of favor for reasons mentioned. Its a bit messy & can varnish more-so than synthetic. Some of the fuel blenders sell their (premix) oil separately so you could go that way with the circulating lubrication system IMO.
What is probably THE most important thing for glow engines is maintenance ritual. If the engine is going to be parked for a couple of months, best to remove the plugs & partial disassemble to the extent you can flood the internals liberally with a good quality oil so that the important surfaces are all coated. I just store engines this way in a ziplock bag. When it comes time to run, drain this oil out, flush with a bit of fuel & ready to go again. RC after run oil is sold for this purpose but like most things, opinions vary. Some blend their own. Some from the high performance community advocate pneumatic tool oil for this purpose. I've used both successfully. The key thing is it coats & protects from corrosion in the down time & must flush away with no real residue or compatibility issues. I'm leary of people who use gear oil or ATF oil because some of those blends don't play well with brass & bronze (of which we have several parts in the radial). Other considerations like silicon O-rings, seals, synthetic gaskets are sensitive to certain ingredients. I steer away from WD-40 for this & other reasons.
Great Planes After Run Engine Oil 2 fl oz
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Hope this helps!