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Your Reviewer

My Credentials
So who's doing this reviewing then?

Well I've been building and flying or driving radio controlled models for over 40 years and during that time I like to think I've built up a reasonable amount of knowledge.

I'm also a qualified electronics engineer who has worked in radio frequency, analog, digital systems and software for more than three decades. In fact I designed and built my first RC set back in 1969.

For the past nine years I've also been involved in the design and manufacture of some rather sophisticated engine technology and UAV flight control systems.

So, chances are I've been there, done that and have a huge pile of tee shirts to prove it.

Right now I'm heavily into 3D flying and enjoy all aspects of the RC hobby. I may be old but I don't feel it.

In the Pipeline

Here's just a little bit of what's to come on this site...

RC explained: Demystifying terms such as PCM, PPM dual conversion, single conversion, full-range etc., this feature will explain it all.

Cheap Chinese Engines: Just how good are those cheap Chinese glow and gas engines that sell for half the price of their "brand-name" equivalent? I put several to the test.

Build your own radio gear?: Back in the old days, building your own RC gear was not uncommon and now the arrival of 2.4GHz has made it practical again.


Model engine lubricants


oils for glow engines

What type of oil?

There was a time when the only oil used for glow-plug model engines was castor oil.

Castor is a natural oil obtained from the castor bean and it has many valuable properties from the perspective of a model engine lubricant.

Firstly, it is very slippery -- which is to say it has great lubricity.

Secondly it has a very high film strength.

Why is film strength important?

Well oils protect our engines by ensuring that there's no actual contact between the metal parts. As soon as metal touches metal, you get wear so it's the oils job to keep the moving parts from actually touching and it does this by forming a thin film between them.

In the case of castor oil, this film is very tough and it requires a lot of pressure to force metal surfaces together when they're separated by a microscopic layer.

Another excellent property of castor oil is that when it gets very hot, it doesn't just burn or boil away into nothing -- it undergoes an astonishing change. It polymerizes.

Polymerizing is when the thin film of liquid castor oil turns into a solid (but still slippery) film somewhat like plastic.

Even when an engine is significantly overheated, this polymerized castor layer can help prevent the metal to metal contact which kills engines.

So, after reading all this you might think that castor oil is the perfect model engine lubricant - and there are some folks who will agree with you.

However, castor does have its drawbacks.

First, it is a very viscous oil, which means that the thin film it creates tends to produce drag between the moving parts. This is most obvious when temperatures are low. A lower viscosity oil will usually allow an engine to produce more power because its drag is lower.

Secondly, the very thing that makes castor such a good oil at extreme temperatures (polymerization) also means that even the best castor eventually produces a build-up of carbon and a residue often referred to as "varnish" inside the engine.

You can often tell an engine that's been run with castor oil in the fuel because the cylinder and muffler will eventually become stained brown or even black, by this polymerized castor oil. Eventually, this varnish can build up to the point where it adversely affects the engine's performance -- particularly in the case of 4-stroke engines where carbon on the exhaust valve can impede the flow of exhaust gasses and varnish can cause the valves to stick.

So is there something better than castor oil?

Well yes and no.

Around the early 1980s, a number of synthetic oils were developed and these offer some benefits (but some limitations) when compared to castor.

Firstly, these oils tend to significantly reduce the amount of carbon and other deposits that form inside an engine. Most of these oils simply don't burn or burn with very little ash.

Secondly, these oils are usually much lower in viscosity than castor but they maintain what viscosity they do have even at high temperatures. This means that the drag produced by the oil film is lower and therefore you can often see a performance increase when switching from a castor oil to a synthetic one.

Unfortunately not all synthetics are born equal.

In the USA, most of the common synthetics are made from a base called Polyaklylene Glycol (PAG), a substance not too dissimilar to anti-freeze.

This oil is cheap, readily available and does an adequate job of providing lubrication when used in adequate quantities (17%-25%). Most PAG lubricants are actually designed for use in airconditioning systems and refrigeration pumps. Unfortunately, they're not really designed for the high temperatures often found in model engines which means that when this oil is used as a lubricant for model glow motors, you must be very careful to avoid lean runs.

More expensive synthetics are usually made from an ester base. These oils offer a number of advantages over PAG synthetics. Those benefits include most stable viscosity, better hi-temperature performance and a lower volatility.

To the best of my knowledge, most US-based synthetics are PAG-based (with the exception of the oils used by Cooper Fuels) and most European synthetics are Ester-based.

This explains why most US fuel manufacturers use higher oil-percentages than their European counterparts. While it's normal to have 17% or more oil in the USA, the Europeans are getting excellent results from fuels that contain as little as 10% of ester-based synthetic oils.

But as you've already seen, synthetics are not without their weaknesses, which is why you can now also by oils that are a blend of synth and castor.

These appear to offer the best of both worlds -- the clean-burning, low friction of synthetic oil with the ultra-hi temperature and corrosion resistance of castor oil.

Which brand/type of oil is best?

Given that there are so many oils and fuels using them on the market, how can you tell which is the best?

Which oil will give the best performance or the longest engine life?

Well that's the subject of an upcoming feature here on

So bookmark this site and come back soon when all the major oil brands and formulations are compared and tested.

Back to part 1

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The Blog

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Here's a blog that will keep you informed just what's going on behind the scenes at RC Model Reviews and also tells you a little more about myself.

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