Am shaking my head reading all you boys talking about the Biggest Bottles...
size don't count fellas, in fact large bottles of fuel are often bad.
Ok, time for some:
NITRO FUEL BASICS 101
Some chemistry... Nitro model fuel is a mixture of
<LI>Oil: 10-20% by volume</LI>
<LI>Nitromethane: 5, 10, 15, 20 and up to 40% for some racing fuels</LI>
<LI>Methanol (methy alcohol): the rest of it</LI>
<LI>Colouring, perfumes: sometimes added in tiny quantities</LI>
Your engine doesn't have an oil supply, it gets all its lubrication from the fuel going through it. If oil isn't coming out of your tailpipe, there might be insufficient oil going in - BAD!! Run your engine rich for longetivity, that feeds it lots of oil.
Castor oil has been used for decades... if its pure, it works great. Castor makes lots of nice smoke too (no smoke = no oil = BAD). However there's sometimes doubt as to quality of the castor in some fuels - with castor as in everything else, you pay for what you get - there's cheap & then there's the good pure stuff.
Synthetics don't make as much smoke normally and usually don't work as well under high-stress situations... would be better for low-stress airplanes its usually said.
Contrary to popular opinion... Nitromethane doesn't actually create 'power' by burning. No, its there to supply "oxygen" to the engine so it can burn its true fuel (methanol) better. Think of it like an RC nitrous oxide NOS setup.
Methanol is the burning bit.
However Methanol is ALSO very hygroscopic. It picks up water moisture from the air, and that makes the fuel go Off. Stale fuel doesn't burn well & makes your engine very hard to start, won't idle nicely and just plain difficult.
Generally speaking...
don't keep your fuel more than 3-6 mths. That's TOTAL TIME folks, from the time the manufacturer bottled it at their factory. And once you've opened the bottle and you recap it half-used, it will go off even faster.
Good Fuel tips:-
<UL>
<LI>Buy multiple
smaller bottles... there's usually higher turnover of small bottles so the stocks are fresher.</LI>
<LI>Buy fuel
more often, don't buy more than what you're going to use within a month. Once open (texta the date on the bottle), use it up within a month or throw it away.</LI>
<LI>Always
immediately re-seal the bottle after topping up. Don't leave it uncorked all day whilst you play.</LI>
<LI>Don't change nitro % willynilly.
Stick to the same % as when you've run in the engine. Some say you should even do run-in again when changing your %. There isn't much reason to use more than 10-15% for bashing, its just more expensive for not much gain. </LI>
<LI>Avoid "imported" fuels... this is one industry were
Local is Better. Foreign stuff would have spent several months in the distribution channel and many weeks on a boat (sea = damp!) - so unless you can
buy fuel in TIN CANs (eg K&B brand), stay clear of all imported plastic bottles. Brandnames are worthless -
Australia produces tons of methane/methanol too!</LI>
<LI>I'd also avoid any fuel that has some serious amts of colouring (purple? deep red?) and anything that has a fruity smell added to it. Both do nothing for combustion.</LI>
<LI>
Don't store it on a concrete garage floor - that's damp! If it has to sit on the floor, sit it on a sheet of polystyrene foam or similar insulation/waterproof.</LI>
<LI>If your storage spot sees a big variance in temperature (hot day, night cold)everyday, you should consider
putting your fuel into an Esky or thermal bag.</LI>
<LI>If you finish playing and there's still fuel in the tank... DON'T put that fuel back into the bottle!!! Throw the tank contents out immediately.</LI>
<LI>Always run a
fuel filter, offroad especially.</LI>[/list]
And there's much to be said about using
After Run Oil in your engine too, before putting it away.
But that's another story.