When you are starting off you will want to buy your fuel pre mixed. Get at least a couple of litres, four would be better.
All glow plug engines run on a combination of methanol and oil. Only oils that will blend with an alcohol fuel can be used. Originally the old favourite was castor oil but very few people use it nowadays. Most glow engine flyers now use synthetic oils, which not only lubricate but also limit foaming and clean the engine etc. You can use a lower oil content with synthetic oils and the most common mix is around the 18% mark as opposed to the 25 with the old castor. Many of these synthetic oils have some castor in them, however the blue oil known as Cool Power does not and most people mix about 5% castor into it themselves. If you are using this oil I highly recommend that you have about 5% castor put in it, your motor will run much cooler. The down side of castor is that it leaves a sticky residue on your model after you have run the engine. This can be easily wiped off with a bit of diluted dish washing liquid, a small price to pay for keeping your engine running sweetly.
The brand names of the synthetic oils that you will come across include Redline, Pennzoil, CoolPower, PowerMaster and Klotz.
Methanol is available from most fuel depots (not service stations). They all have different names for it, but make sure you get the methanol without the acetone in it which is called Racing A.
Our Club supplies synthetic oil and methanol for slightly above cost to the members, or you can buy it from most hobby outlets. As I have mentioned above, it’s easier to buy your fuel premixed from your hobby supplier when you're starting off.
Many people also run a percentage of Nitromethane, commonly called Nitro (The same stuff used in drag racing). Nitro gives the motor a bit of extra power and smoothes out the low speed running of many bigger engines. Many people think that nitro boosts up the octane level of fuel but this is not the case. The way nitro works is actually quite technical, in a nut shell it generates more oxygen for the engine which has a similar effect as a supercharger. Nitro is recommend by the manufacturers of four stroke engines for smoother running. Nitro has a couple of downsides too, one is the cost, at $40+ a litre it soon boosts the price of your fuel too, and prolonged use can cause engines to rust internally. The most common mix of nitro is around 5% - 10% . Specialist flyers like 'Pattern' and helicopters can use up to 25%. Generally speaking, the two stroke engine in your trainer does not need any nitro.
If you plan to mix up your own fuel, which you probably will later on down the track as it is much cheaper that way, don't mix up too much at once. It depends on how much flying you are doing, but about four litres is generally enough. Fuel does go stale if left to stand for a while, it will still work but it looses a bit of it's zip. Be careful with methanol, it is absorbed by the skin and can cause a few problems. Keep your container well sealed as it also absorbs moisture.
Many of the larger models use petrol engines. These run on a very similar mix as your 2 stroke lawn mower, unleaded petrol mixed with oil. Again, most owners use the synthetic oil instead of the mineral two stroke oil. It is mixed in similar proportions as a mower as well, usually around 40:1. Occasional you will come across a model running a four stroke petrol engine, these run on straight petrol but they are very rare.
Diesel fuel for model engines is not that common these days. The reason for this is that it is mainly ether and it is VERY expense. The best thing about model diesel fuel is the smell, it's great. The mix is usually ether and caster. Before you decide to run a diesel engine make sure that you can source the fuel, it is very rare.
Contributed by Brian Carson - SMF Senior Instructor (Note from Bob Cottle - Webmaster)