If you require instructions on how to operate your Cox engine, please see our guide

 Cox Engine Operating Instructions

Click here for our guide Is this the end of Cox?

• Cox engines typically run on what is termed "1/2A fuel", a fuel with high nitro content and containing some castor oil instead of synthetic oil only. This fuel mixture is becoming increasingly difficult to obtain. Often, when referring to "1/2A" in hobby stores, it will elicit blank stares.

• Typically, Cox engines will run on a fuel mix that contains 15 - 35% Nitro, whereas the higher nitro content will lead to higher RPM's but also to a shortened engine life. The Tee Dee series are better suited to higher nitro content, whereas the basic production engines are best run with a lower nitro content. Operating your Cox engine with less than 20% nitro content might make adjusting the needle valve somewhat quirky.

• The biggest challenge is finding pre-mixed fuel that contains castor oil, as most fuels sold nowadays contain synthetic oil only, which can lead to premature failure of the engine's crankcase bushing and/or ball socket. There are some "1/2A" fuels on the market that contain 100% synthetic oil. We recommend you do not run your Cox engine on such a mixture.

• Cox recommends a fuel mix containing 20% castor oil. Under strict racing conditions, as little as 5% castor oil (and the balance synthetic) is required to protect the engine for it's short racing life but is not recommended for recreational flying, where longevity of engine life is desired. To be on the safe side, we recommend at least 10% castor oil and 10% synthetic oil. The upside of using a 50/50 castor/synthetic mix is that it will help reduce varnishing and leave less oil residue on the model.

• DIESEL: For those of you that have converted your Cox engine with a diesel head, you will require a diesel fuel mix. This fuel is available from hobby stores or you mix it yourself.
  

So, what is the mix of 1/2A fuel?

Can I mix it myself?

• Absolutely! Many modellers mix their own fuel. Using the formula previously mentioned, here are some suggestions where to find suitable ingredients. Your local "Yellow Pages" is likely a good place to start your search.

• Methanol can usually be obtained from outfits that supply fuel for race cars, or from chemical supply houses.

• Castor oil is generally available on-line, at off-road motorcycle shops, at grocery stores, pharmacies, etc. You will only require industrial grade castor oil and there is no need to purchase the more expensive food-grade version. Klotz BeNol is a good choice and available at motorcycle shops. Klotz KL-200 is a good choice for synthetic oil and is also available at motorcycle shops. "Sig" also sells both aforementioned oils.
  

• Nitro, well good luck! This product is somewhat controlled and fairly difficult to purchase. It's the stuff that has the boys in suits and dark sunglasses taking an interest in you when you inquire about it. Your best bet, again, is contacting outfits that supply fuel for automobile/boat racing or chemical supply companies. Be prepared to answer questions :)

• DIESEL: Ether in itself is a bit difficult to purchase, just like nitro. Try a chemical supply house. More expensive but the same thing, is lighter fluid.

• DIESEL: Kerosene is quite easily obtained at sporting goods stores, in their camping section. Use the unscented variety.

This guide has been brought to you by xenalook! and Bob Beecroft

Without Bob's help, this guide would not have been possible - Thanks Bob!

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