hi. i got my plane together, got a new engine, went to the hobby shop and they gave me fuel with 15% nitro, and 20% oil. now that my engine is broken in, do i need to get different fuel to fly with, or can i use the rest of what i have? also, once its gone, can i change to lower percentages? thanks for any help.

Really depends on what engine you have. Some brands call for diffrent % of nitro. Guessing that the LHS knows what engine you have, they have given you the "standard" airplane fuel. I run 15% nitro 20% oil in all my engines, but others use 10%, 5%, or no nitro glow fuel as well. If it runs well on what you have; stick with it, there are enough other variables out there to trip you up!

You can use up what you have then change if you like. You forgot to mention what engine you have but most engines can use any standard brands of fuel. Nitro doesn't mater a lot but the oil most manufactures state the ammount and type of oil they would like you to run. Most fuels are either full synthitc or a blended oil. The blends usually contain a bit of Castor oil.

The only reason I can think of to change fuels is to save a couple of bucks the next time you need a gallon. 10% nitro usually runs a couple of dollars less than 15%.

fuel is made up of 3 parts.....oil, to lube and carry away heat,.... methol alcohol, which is the real fuel, it's what we burn...nitro which acts as an oxidizer to help the burn.....
Nitro will cause the burn to be a little hotter but not enough to notice if your engine is properly tuned....and wilkl usually give you a better idle.....As said above some engines by brand not by a particular engine likes a lower nitro content.
So to answer your question there is no need to change nitro content.....but once the engine is broke in you need to lean out the mixture for more power...but do not run too lean

the engine i have in my trainer is an ASP .40. and jp, you are correct, i went to the LHS, told them what engine i had, he came back with the fuel  i ended up getting.   i just have a mess of oil comming out of my exhaust, and i keep leaning back. im sure the engine is in the ballpark on tuning, but i guess my question is, once im sure i tune it correctly, can i get fuel with a little less oil in it so i dont have so much oil to clean every time i run the engine?

Well You're secret on the engine, however I think you have an OS 40ax and an OS 46.

The fuel will do fine, especially since the engine is "broken in."

15% nitro is the main fuel because relatively new modelers are led to believe they need the high-priced spread so the dealers can SELL the high priced spread.

With today's common engines, mostly developed with a compression ratio for foreign markets where nitro is not availabel, 5% nitro does fine. Most Eurpean fliers find 80% methanol with 20% oil to do just fine. (Required in FAI competition)

One of the biggest fuel frauds that still exists is that the old Cox .049 - .099 need 20-30% nitro to run well. That is fine for competition Free Flight, CL Speed and Combat, however for sport models they do extremely well using 10% nitro and 25% oil with 1/2 castor oil. Small engines need OIL to cool them.
I keep a Fox 19 CL model, now over 25 years running, and 4 Cox .049 models, 10 t0 15 years old, to have fun with kids/grand kids every so often. Never burn a glo-plug, easy starting, and solid running.
In RC I run everything from .40 to 1.10 glow and larger gassers.

The point of all this is that toy airplane commercial markets spread a lot of rumors about what is REQUIRED. Many RC fliers follow the "in" gossip and really have no clue what it all means. Don't pay a lot of attention to such rumor mongering. When you become a hard-core competition flier then you are in another world, so follow what you think that world requires. BTDT too. Have fun!

Wow, what a conspiracy theory! LHS's are pushing higher nitro fuel that people don't need in order to boost their profits. That extra $3 a gallon must be a really big deal!

The truth is that the fuel you have is good stuff and the hobby shop did you right. Your engine will run fine on lower nitro if you want to save a few dollars though, and you probably won't notice the difference in horsepower on trainers and most sport planes. You shouldn't go lower on oil content though. Cleaning the slimy castor residue off the plane is part of the flying field ritual for everyone who flies glow. Depending on your muffler location, an exhaust deflector might help.

Goo out of the exhaust is a very good thing.

Tom

ok. thanks for all the input. its not really about the money, but the time, and mess involved in cleaning the plane up. ill see whats available, and also look at an exhaust deflector. now if i do end up changing fuels, a retune is in order, correct? damn, all this, and i still havent put her in the air yet.! oh well, im still having fun.

sounds like you may still be a little rich...but that is a good thing....I've never heard of an engine destoryed by too rich a mixture....
besides nitro content has nothing to do with oil content until you get up to 30 per cent nitro

Well, a re-tune is always necessary, every day in fact. Sometimes, a couple times a day to get things optimized. Atmospheric conditions change from day to day, and in some cases, from hour to hour or even more frequently... but this is not a weather forum, it's about your engine and fuel.

You should tune the engine the first time you start up at the field that day. You get best results that way and become more familiar with the tuning process and have more consistent runs from flight to flight.

Regarding fuel, I've been using S&W 15% nitro content for years now. Not that I am pushing S&W, but it's that I started with it and never changed.. mainly because that was what was available at the LHS and what my instructor used (we seem to follow that path.. radio systems, engines, fuel, and so on), it's just human nature. And, it becomes the best of everything else we could ever get... of course...

The point is, as has been stated, what you have is what you have and what's available to you. Stick with it, unless some major reason prevents you from doing so (your LHS closes down and you go to another that doesn't carry your favorite brand of fuel or some such thing like that).

The main point is, learn to tune daily or more as necessary, and stick with what works for you.

CGr.

Unfourtunatly, all that goo coming out of your exhaust is exactly what should be there. That left over oil is what was cooling and lubricating your engine. If you lean to the point the goo isn't there, neither is the cooling or lubricating your engine needs. You can loosen the bolt that holds your muffler halves together, and turn the small outlet spout to a better angle to try and keep some of the mess off your plane, as well as using an exhaust deflactor. Or do as the rest of us have, invest in paper towels and a cleaner to wipe off your plane at the end of the day. I personally use dollar store window cleaner with about 1/4 of the bottle dumped and replaced with alcohol. (but that's a diffrent post all together)

Yeah, there was a pretty good thread going last week about cleaners and the formulas that many RC folks use... but it's always nice to hear about someone else's success stories. I ought to build a database of cleaners... [X(] just kidding, of course.

Some switch to electric because of the goo on the wing and fuselage, but that has it's drawbacks too. I fly both but prefer glow and live with the mess.

But, your point was well taken. That goo is is a necessary disadvantage. For instance, S&W is red. So, the goo that I see on the wing is red. If it is black or gray, well, that starts to point at something going wrong.. any change in color (after initial break in, that is) could give you some clue as to there being something wrong.

So, tlojak38 , don't fret about the crap on the wings... take a good look at it and just clean it off once done for the day.. or whenever you want.

CGr.

CGRetired, your idea of a database for cleaners sounds good to me. It can be passed around to anyone asking these same questions in the future. It might help newcomers to the hobby from shying away from nitro engines.

G'day tlojak38

Goo is good. It means your engine is being properly lubricated.

And just be thankful that you are not a World War I pilot flying a rotary engine in something like a Sopwith Camel. They had engines which used total loss lubrication systems like our glow engines but they used several gallons of nice sticky castor oil per hour and a lot of it came back in the face of the pilot. Those goggles were not just for the wind and the silk scarves were not just to look cool. They had to have something handy to wipe the oil off their faces while being shot at and trying to down the enemy.

AND, those engines did not even have a proper throttle. Just switchable magnetos so the pilot could turn off some cylinders to slow things down a bit. And we thing we have it tough with a bit of oil on our planes!

I've been using morgan fuels coolpower full synthetic GREEN 10% nitro.I use it all the time, break-ins,4 strokes, and 2 strokes. I have Never had a problem with heat, rough running engines,or brown junk baking to the outside of the engine/mufflers. I recommend this fuel to everyone I talk to. It helps my engines run cool,clean, and I think it smells better when burning. 

The reason I grinned at the prospect of a database is that there are so many different variants of someone's home brew cleaner that it would be almost impossible to get them all straight.

Can you imagine, RCU-Joe #1 says use this forumua. Then RCU-JOE#2 says "Well, that's fine, but I use an ounce of alcohol per gallon and it works better than yours". Then in comes RCU-Joe#3 that says, "this is all crap. I buy glass cleaner from the Dollar store and add one cup of ammonia and THAT works best".

I may give it a shot, though. That last series of posts had about a dozen (exaggeration I"m sure) formulas.. then looking back at previous threads where cleaners came up, well, anyway, you get the idea.

Let me ponder it and if I do it, I'll get it posted here.

CGr.

A data base of cleaning methods, can you imagine? I think everyone has thier own methods, the list would go on forever! I had been running Byron fuels 15% (because that's what was available), but now that the good LHS closed down and the owner moved to AZ, I'm stuck with a car shop that keeps a few plane things in stock. The fuel (which I haven't ran yet) is sold in square metal cans and mixed by some company in San Antonio. (still 15% nitro, 20% oil) If not for that, I'd have stuck with Byron forever, because it's what worked and was available.

Exactly my point, JP.

CGr.

yea, guess I was trying to help you make your point.

I notice airtime mentioned synthetic fuel, that's not a bad way to go. I have tried it, not the green though and it is a much cleaner fuel. The bulk of the snot is the Castor oil. My number one brand fuel has always been Power Master 15/18. The 18% oil is fine but being a blended fuel there is still a lot of nasty snot blowing out. When I could no longer get Power Master I went with Wild Cat 15/16, much cleaner but 16% oil gave me pause so I added in two ounces of Klotz oil, that brought back the snot factor though. I'm now able to get the Power Master 15/18 again so I will be leaving my Klotz for my gas engines. If it's just the clean up that's the problem then buy a jug of full synthetic and give that a try. By placing my engines on there side or inverted I'm able to deflect the snot away and have very little clean up. I have one plane with an upright engine and it's a total mess after one flight, even with the deflector. There is just no good place to deflect the exhaust.

I'll offer my best cleaning tip. Before even using the solvent, wipe the plane down with a dry microfiber rag from the auto parts store. They are so absorbent they actually lift the residue off the covering instead of smearing it around. On some days just the rag leaves my planes clean to the touch, and I toss it in the wash after 3-4 flying sessions. I still hit it with cleaner to get the stuff out of the seams and corners, but the job is much easier this way.

HI
DO YOU WANT your plane to be clean OR do you want your engine to run real good and last a long time -,the choice is yours -,you must use some castor oil in a two stroke glo engine if you are looking for long term performance and longevity-,-clean the plane and get over it ! -full syn fuel does not give the metal protection that castor does when engine temp rise and MAY cause serious damage
i run 15 % MORGAN OMEGA in all my glo engines,per CLARENCE LEE not a good idea to reduce the nitro % as the piston and linner will not produce the same head temps,so the parts will not expand and seat to each other as they were doing before
i find it best for engine life -,to run a given engine on the same % and brand of fueland use one size prop ( once you properly prop your airframe )
building ,flying and running two cycle glo engines for 26 years-,MORE THAN MOST-,less than a few
ENJOY BEST RGARDS TONY

It HAS to be the GREEN kind if you're going to try this fuel. I've tried the pink(which also says full synthetic) and it was so bad I only made it through about a third of a gallon before giving it away!
It had the engines running hotter, was horrible during tuning, had several deadsticks and the worst was I started getting the brown gunk on the outside of my engines. Went straight to the LHS and grabbed two more gallons of green and haven't ever tried anything else.