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Is there a difference in fuel between Cox airplanes, and cars?

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Old 01-02-2014, 06:00 PM
  #1
mtrain
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Default Is there a difference in fuel between Cox airplanes, and cars?

I live in a small town where there is only one hobby shop. I went in today to ask if they had any fuel for my old 70's Cox Stuka.

The owner said that he had fuel, but it was for the cars, and he didn't think it would work on the planes, but he said that people had bought it for planes, and he never had any complaint.

Anyway its a 20% nitro fuel.

So can I just buy the fuel he has, and save myself the trouble of buying it on the net?

Thanks.
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Old 01-03-2014, 06:10 AM
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The biggest difference would be the oil content -- I don't know what the car fuel is down to, but I wouldn't run it
in a Cox without checking the oil content and makeup. The Cox engines will want about 20% oil, with at least
half of it Castor oil. We run them all the time on Sig 25% with a 50-50 blend of Castor-Synthetic. I'm guessing
that the car fuel has less oil than that, some of which may be Castor, but not for sure unless you can get the
mfr. specs. You can buy Castor to add to the car fuel, which would make it useable. You still need to know the
specifics about the fuel you start with, so you know how much Castor to add to it.
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Old 01-03-2014, 02:52 PM
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Most car fuels today are in the oil content range of 9% to 12%. One maker does makes a 16% break-in fuel for car engines. When the Cox format engines were designed, airplane fuel was 25% all castor. This level worked fine as it prevented the rod big end from galling on the crankpin, And it also kept the rod ball and piston socket from wearing out prematurely. They also required a higher concentration of nitro in the fuel which usually standardized at 25% to get a smooth even run. I used to run TD's in C/L Combat with nitro content as high as 45% and if I didn't add castor to the 18-20% oil fuels available in the 80's, I would find pieces of the rod "welded" to the crankpin.

Your can use the car fuel, but your going to have to add castor oil or Klotz Benol to it. Easiest way to go to the Walmart pharmacy and buy a 6 ounce bottle of castor oil ($3.00 or less) and add it to a quart of 30% car fuel. If your going to fly a lot of 1/2A, go to a motorcycle shop get the Benol. It runs about $9.00/pint. To get specific, if you get 9% fuel, add 6.75 ounces of castor. If the 12%, add 5.5 ounces. This will get you to the 25% mark in oil and around 25% nitro. You can modify the 16% break-in fuel with less castor/Benol, but you will be below 20 % on the nitro.
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Old 01-12-2014, 06:21 PM
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I use Basher 20% car fuel in my Cox engines, but as Tigrejohn said you need to add some castor. 2oz. too one quart is what I add and have never had any problems.
http://brodak.com/engines/oil/castor-oil-pint.html
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Old 01-14-2014, 12:47 PM
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You bring up a good point on how you corrected the oil deficiency with fuel.

One has to be careful on today's fuels. There is even one brand of fuel marketed under the Cox name, but it falls short of Bernie at Cox International's recommendation of at least 20% oil with at least half of it being Castor. Sig Champion fuel meets this requirement. One can probably use the RC car fuel if they bring it up to specs by adding Castor. The hobby shop may sell Castor oil in bottles. If they don't, a motorcycle shop catering to motor sport competition may have racing Castor, such as Klotz Benol. I've heard one can also use pharmacy grade Castor oil, but I don't have any personal experiences with that to say yea or nay.
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Old 01-14-2014, 02:11 PM
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On the other hand Cox .049's are so common & cheap, that it probably doesn't matter if you wear a couple out using them.

Greg
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Old 01-14-2014, 04:58 PM
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Cheap is relative. Out of curiosity, I checked the US inflation rate. For other countries, inflation rate has varied, but overall this is representative. In 1965, I believe the list price of a Cox .049 Babe Bee was $3.95 US. Rounding to $4, and compounding annually is the average annual rate found on

http://www.usinflationcalculator.com...flation-rates/

Cost in 2013 would be $29.16 US. Cox International's price for their cheapest tank engine, the Cox .049 Skymaster found on

https://coxengines.ca/cox-.049-engine-skymaster.html

is $44.95 US or roughly $45. Price of engines are more now than they were when Leroy Cox was making them. If one downscopes to a tankless engine such as the die cast Sure Start, the cost is $26.95 us or roughly $27, which is slightly cheaper.

Then there is shipping of about $7. Personally I would like to get at least 100 flights or more out of a Cox before having to replace or repair it. That equates roughly to 6 to 8 hours flight time total or a year or two of flying.

So, it depends upon one's philosophy. I'd prefer to keep flying reliably, and not have to worry about a shortened life engine. Thus, I will ensure a reasonable oil content overall with a goodly percentage of Castor oil. It doesn't have to be 50-50, but would like a substantial enough amount to ensure the engine fulfills its normal life expectancy.

As usual, as they say, YMMV (your mileage may vary).
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Old 01-14-2014, 06:40 PM
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George,
As you say cheap is relative. To me a Cox .049 is a disposable object. At one time a Sydney based modeller bought a 44 gallon drum full of them, and was selling them for $5 each. Presumably these were engines that had been returned as "faulty". The ones I got ran faultlessly.

A quick search of eBay shows plenty for sale and many could probably be had for under $20.

Again you can place whatever value you prefer on them. To me if my fuel choices were limited, I'd run them until they ran no more and make a low priced replacement. Others are entitled to make what ever choices their means and experience dictates.

On the overall question of fuel, I make my own, and would encourage anyone who can gather the components to do likewise.
a. It's cheaper
b. You can mix whatever blend you like and
c. You know how well it's been filtered.

Regards

Greg
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Old 01-14-2014, 07:23 PM
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Greg, for one I think that there may be country differences. Here in US, seems we have our share of collectors who for the want of Cox drive the bid prices up to the extent that it is almost useless to bid on them. Besides, I've had my share of E-Bay clunkers and as such am somewhat reluctant to rely on E-bay for engines.

Also, we have a bit of a problem here in the windy southwest. Since moving to the high plains of New Mexico, we don't see the calmer days of other places I've lived. the 1/2A's just don't cut the mustard except for the few rare occasions we have favorable weather.

So, we each have our own philosophies, of which of themselves is neither wrong nor inappropriate. We all approach problems in different manners, but overall I believe we more or less have the same or similar outcomes.

Regarding fuel, yes a few blend their own. Kudos to you that you do your own custom blends. As for me, I am not willing to go to those limits.

So, to each his own.
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Old 02-17-2014, 11:30 AM
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Do NOT buy the Tower Hobbies version of Cox 1/2a glow fuel as it lacks proper lube..
Here is their description:

This is the quart (946ml) Bottle of Super Power 1/2A Fuel from Cox.FEATURES: Premium blend 25% nitro formula is ideal for model airplane, car, or boat use Special 18% oil package consists of 90% synthetic, and 10% castor lubricant blend Latest high-tech synthetics combined with castor protects and lubricates the aluminum journals and plain steel bearings used in
small displacement engines

Sig has great fuel and by the quart with other items is reasonable shipping...BUT the web site absolutely sucks----http://www.sigmfg.com/

They sell pure castor oil and Klots BeNol as well as severl blends of fuel that are very good

Fox also sells good fuel but another maddening web site.... they still sell Missile Mist....grin--- but I can not find the real hot stuff they sold call Fox Blast

Bernie at http://coxengines.ca/ has a lot of great stuff, good web site and has small quantities of castor oil to add to local sourced fuel

another good source for cox engines and parts is Matt at http://www.exmodelengines.com/

bottom line is there is no reason to ruin a good old Cox engine from improper fuel but if you do, there are plenty of parts to make them sing again
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Old 02-17-2014, 11:03 PM
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I think that has been universally agreed upon. Even Bernie at Cox International has recommended at least 20% oil with at least half as Castor for the Cox engines. Sig Champion fuel meets that requirement.
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Old 02-18-2014, 04:13 AM
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George, I agree with you 100%
When I see these questions I try to post with info, web sites and hopefully in the thread we already discussed the need for 20 to 28% castor lube is Cox or old iron piston bushed engines

Every few days or so this question is searched by folks returning to their youth or kids inheriting a box o engines
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Old 02-18-2014, 07:11 AM
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True. Where the Sig fuel is not available, the local hobby shops 95 miles (156 kmh) away. I buy a bottle of Castor and add it. Might be a touch more on cost for my plain bearing iron piston steel cylinder engines, but at least I'm flying. I am told that even with the legacy K&B Sportster AAC aluminum cylinder with a chrome plated aluminum piston plain bearing Schneurle, to run fuel with significant Castor oil and higher overall oil content. Engine got a foul rap on it when modelers ran the motor overly lean or did not use adequate oil content fuel. CL fliers like the .20 Sportster as it will swing a 10x5 prop all day long with adequate power for a .35 sized plane.
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Old 02-18-2014, 08:40 PM
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Quote:
Originally Posted by fredvon4 View Post
Do NOT buy the Tower Hobbies version of Cox 1/2a glow fuel as it lacks proper lube..
Here is their description:

This is the quart (946ml) Bottle of Super Power 1/2A Fuel from Cox.FEATURES: Premium blend 25% nitro formula is ideal for model airplane, car, or boat use Special 18% oil package consists of 90% synthetic, and 10% castor lubricant blend Latest high-tech synthetics combined with castor protects and lubricates the aluminum journals and plain steel bearings used in
small displacement engines

Sig has great fuel and by the quart with other items is reasonable shipping...BUT the web site absolutely sucks----http://www.sigmfg.com/

They sell pure castor oil and Klots BeNol as well as severl blends of fuel that are very good

Fox also sells good fuel but another maddening web site.... they still sell Missile Mist....grin--- but I can not find the real hot stuff they sold call Fox Blast

Bernie at http://coxengines.ca/ has a lot of great stuff, good web site and has small quantities of castor oil to add to local sourced fuel

another good source for cox engines and parts is Matt at http://www.exmodelengines.com/

bottom line is there is no reason to ruin a good old Cox engine from improper fuel but if you do, there are plenty of parts to make them sing again
Unless you want a Tee Dee 051 piston and cylinder, or a Tee dee crankcase, or for that matter pretty much a tee dee anything!
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