Fuels Paradise

[Tim Mackey]

No Andrew you are not.

[Braddock, VC]

I think it's best to use what you want to use, after all the "warranty" on most engines simply isn't worth the paper it's written on.

I remember my first r/c plane back in the 50s, a junior 60 powered by an ed racer, it had a rubber powered escapement to turn the rudder, the transmitter had a tank aerial the batteries were dry and expensive and the engine used a truflex prop and castor for lub.

My latest Junior 60 has an OS 26 SF, lipo batteries and a ubec to power the 2.4ghz rx, the transmitter has nicads and the engine uses an APC prop and prosynth 10% fuel. Castor - you must be joking the world's moved on since then.

[Malcolm Fisher]

John,

Re "Castor - you must be koking..."

 In my initial post, I was referring to the instructions which came with a brand new engine bought only a couple of years ago. The manufacturer, OS, stated that the engine must be run in initially on fuel containing a high 30%  of castor oil and subsquent operation stated 25%. Who am I  to argue with that?

 I agree that most warranties aren't much use and "you pays your money and takes your choice".

 I have already stated that I've used all types of lubricant in my fuels - especially when mixing my own...

[Myron Beaumont]

What ever happened to castrol " R "  Good oil with a lovely smell too  Used to use it in my diesels & my motor bikes  BSA  Gold Star etc going round Mallory Park
 I think it was castor based ?

Over to you Eric !

[Bruce Richards]

Nothing happed to it you can still buy it 

 

Here 

[Braddock, VC]

Malcolm, I think the os wankel engine is the one that proves the rule.

I stick to my guns and say you get what you pay for, castor straight is about 2/3 the cost of prosynth straight, after running the engine on prosynth, by the next flying session the engine remains free and clean. Can't say the same about the airframe, it gets as slimy as a slug's bottom and the only positive feeling I get from that is that the oil must be all over the moving parts inside the engine.
Incidentally, I don't use after run, at the end of each flying session I run the engine at full speed on the ground for about half a minute and pull the fuel pipe off to stop it. This apparently makes the engine hot enough to evaporate off any methanol in the crankcase thus reducing the risk of internal corrosion.

One man's meat is another man's castor .

[Myron Beaumont]

Bruce  Thanks for the link re- Castrol R

Shot up in price hasn't it and it doesn't come from an Arabian oil well  !!!

[Rick Tee]

A google of the synthetic oil used in model engine fuels will reveal the spec sheets. Synthetic oils burn off cleanly leaving low or no deposites where as castor leaves a gummy deposite. The main advantages of castor are it burns off at a higher temp than synthetic so if you have a lean run it's less likely to damage your engine and is better at rust prevention. Most modern synthtic fuels contain some 2% - 3% castor giving the benifits of castor without the drawbacks. The wankle is a fairly uncommon model engine so i'd stick with the makers recomendation and use castor based fuel.

[Ernie]

Hi guys

I think we should all use castor.

Who cares about ruined valves, baked on deposits, and the sticky airframe?

what about that absolutely fabulous smell?

 

ernie

[Bill R]

Seems like this thread has died a death!

All the comments are well meaning but some do not appreciate the actual properties of good old castor oil. It was the only oil that could sucessfully lubricate jet turbines in the early days of jet propulsion.  The expert on castor oil and the properties states that when castor is "overcooked" it actually performs better as a lubricant as the molecules bind together and are "stickier" thereby adhering better to the metal of the moving parts. Synthetic oil has made leaps and bounds as a superb lubricant but cannot replicate the properties of Castor at elevated temperatures. Once synthetic oil reaches breakdown temperatures it ceases to be a lubricant and breaks up and burns off very quickly. Castor on the other hand continues to lubricate long after the synthetic gives up the ghost. The engine can and will "gum up" if it is run at elevated temperatures on pure castor and the residue of dirty dark brown colour is the result. All engines should use a minimum of 2% castor and you will find that most synthetic oil fuels have a minimum castor content in the synthetic blend. When you run too lean or too hot it will be the castor content that will probably prevent the engine from seizing. If you use Irvine 10 fuel [synthetic blended oil]the best guide for fuel /air mix is a slight discolouratiuon of the exhausted oil from a red colour to a slightly darker red/brown residue for maximum grunt without seizure. This shows the 2% castor in the blend is getting nice and warm!

[William Morrison]

The synthetic - Castor argument goes on forever in the US too.  The fact is that Castor burns at a higher temperature than most synthetics, thus a great deal of it is expended after combustion and it makes a mess.  But Castor as a lubricant gets better with temperature and does indeed coat everything inside and outside our engines.  This coating ends up being varnish, discoloring the engine and the silencer (muffler as we say here in the  US).  Bottom line is that a little Castor in the mix is good insurance.  If you can tolerate the mess, use more Castor than less. Engines that have and use Castor as a lubricant in the fuel generally out last those that do not have any Castor in the fuel.

 

It is your engine, do what you want with it.  If you want it  to last a long time, make sure there is some Castor in the fuel, maybe 2 to 4% regardless of whether it is a two cycle or four cycle engine.

 

BTW Castor also works in Gasoline engines.

 

Cheers,

 

Chip

[Ernie]

Hi Guys

How much castor do I need to get the smell

ernie 

[flytilbroke]

If an "normal" two stroke glow engine gets hot enough to burn off todays synthetic oil in commercial methanol base fuel something is exceedingly wrong. Before that is likely to happen, the engine really is not running well and likely to have expanded components which will stop it working. My models engines, as well as all the others I have seen, DO sacrifice the oil out the exhaust in the same way that castor gets ejected.

 

Use your eyes gents and observe for yourself, don't just repeat old codgers tales.

[Peter Beeney]

   Just to add some useless info. to the interesting discussion about fuel, if I may, I’ve always considered one reason why castor oil is, or should that be was, so popular in glow fuel is because it is instantly soluble in methanol. Whereas if you tried to to use a mineral oil you would perhaps need all sorts of additives to make it mix together. I have a feeling that when synthetic oil was first used with methanol it did have some sort of emulsifier to make the oil disperse in the methanol more easily. I’m not sure if that’s still used today.       Castor is a vegetable based material, as is methanol, or wood alcohol, although I have read somewhere these days it’s mainly a by-product of gas production. Castor oil will only mix? with paraffin or diesel to make model diesel fuel with the addition of a generous helping, of say 30%, of ether. When we first started tinkering with small diesels, circa ’50/51, we soon found that once started the engine would run on a simple mix of paraffin or diesel and mineral oil, albeit not too well, it wanted a dab of amyl nitrate, or ethyl nitrite, or other such exotic dope. Unfortunately the chemist wouldn’t sell it to us. Likewise with ether. Still, I was only eleven! And my brother was nine. From a very dim and distant memory, I think the KK model diesel fuel was - ether, paraffin and mineral oil, in equal quantities, with a teaspoonful of amyl nitrate, or similar.
   I never did much like the odour of castor based glow fuel, both neat and burnt, so when synthetic oil appeared on the scene around the late seventies to early eighties, I started to use that. Wasn’t too fond of that smell much, either. Is that significant, ‘cos some exhaust fumes are now quite scented! Another disadvantage I soon found was that the exhaust residue on the fuz etc. was a good paint stripper! However, since then the system that I’ve used has at least been consistent. I buy eight gallons of straight synthetic, plus a gallon of plain methanol, at the time, always from the same source. This synthetic oil based fuel has a dash of castor in it, for the benefit of those pilots ‘that don’t quite get it right,’ making a total of about 17% oil. Adding 1 pint of methanol to each gallon thins it to around 15% oil. I use this for practically everything. I have had some problems over the years, but even they are not always what they seem. For instance, at one time, I had some Irvine 36 rear bearings breaking up. When I spoke to the-man-in-the-know, he said, ‘It’s not you, Irvine’s have a (big) problem with a batch of bearings.’ It seems I was not alone! The extra methanol also has the benefit of making the total 9 gallons relatively cheaper. The general performance isn’t bad, either, today I clocked my Irvine 53 Mkll at 11700 rpm, static, on an 11× 8 ACP, in an ancient Flair Patriot. Allowing for 20% unloading in the air, that’s 106 mph! But that’s theoretical, including the unloading factor, so if we knock off 20% for prop slip, drag, and a dirty windscreen, then we are back at 85 mph. Which might indeed be quite near the button, it’s fairly hurry-up stuff indeed! I do like models with a bit of ‘get up and go!’ For four-stokes, particularly Saito, I add a generous 10% nitromethane. They instantly seem to run faster, smoother and even slightly less noisy.
   With regard to the castor verses synthetic debate I wonder what would happen if someone approached a classic marque, such as BMW or Aston Martin, and said they were going to fill the sump of their car with castor oil, because they thought it was better than the existing stuff. Which I suspect, but don’t know for sure, surely has to be a top grade super synthetic oil. I think the polite retort might be, “You’re on your own from now on in, sunshine!” Circa 1960‘s, one of our tribe put Castrol R in his road bike, a 500cc single, and after a short time it seized up. Solid! When we eventually got it apart it seemed as though the viscosity was much too heavy for the oil pump. Little or no oil circulation. I’m thinking the racing bikers back in days gone by only used it very hot. Someone told him to put a few drops in the tank, if he wanted the smell! Can you still buy Castrol R?
   I reckon the only time you get to sniff this aroma now is at a vintage motor cycle race meeting. Manx Norton’s and AJ 7R’s etc. And the smell will come from the mix in the fuel tank, rather than from the oil in the oil tank.
   Apart from aeromodellers, does anyone else still use castor oil as an engine lubricant any more?

   The ‘synthetic’ approach certainly seems to work for me.    PB

[Tim Mackey]

£11.25 a litre

[Phil Claridge]

myron, i was up at pembray race circuit on easter sunday they had a 50's 60's 70's motor bike meeting, and the aroma of castrol r came drifting by on the wind to the flying site about half a mile away

[Martin Harris - Moderator]

Posted by Peter Beeney on 06/04/2010 18:22:40:

Circa 1960‘s, one of our tribe put Castrol R in his road bike, a 500cc single, and after a short time it seized up. Solid! When we eventually got it apart it seemed as though the viscosity was much too heavy for the oil pump. 

 

I recall the advice in the early 70s was that if you were going to run an engine on castor - then still the accepted "ultimate" racing lube - you HAD to strip and clean every trace of mineral oil before doing so or it would "gum up".

 

 Someone told him to put a few drops in the tank, if he wanted the smell! 

 

..and that was the general advice back then in Motorcycle Mechanics magazine etc. - and yes, we did club together to buy a tin for our Tiger Cubs and Honda 175s... and they did smell good! 

 

[Peter Beeney]

 

   Martin, I’m sure you are absolutely spot on, I’d have thought that using Castrol R oil could be fraught. In fact, if R indicates ‘Racing‘ then that implies that’s for use in engines that are taken apart on a regular basis, when at the very least, everything would be cleaned up, and the oil most likely changed anyway.

   You mentioned the Honda 175, I always thought that and the 125 were outstanding performers. Back in those days I use to go to the IOM, to watch the TT races. In ’61 or ’62 (I think!} Bob McIntyre, The Flying Scotsman, wheeled out a new Honda, a jaw-dropping 4 cylinder 250! As I remember, he won the 250cc race and then entered the 350, which he led for one lap, until something broke and he had to retire. Of course I’ve no idea what oil they were using, but I’d be surprised if it were castor. The new detergent mineral oils were coming in then, I’m sure there would have been a lot a lot of pressure to use these. To advertise as ‘Race proven?‘
   Ten years before, too young to ride, we also used to read the motorcycle mags, I forget what they were called, but one was blue and the other green, I think they were ‘The Motorcycle’ and ‘Motorcycling’. Some of my mates had older brothers with bikes, and the magazines came our way from there. I can certainly remember that we constantly scanned the ads from the likes of ‘Pride and Clark’ to see what our next star buy was going to be! Although I got my licence on a small bike, in those days there were no limits as to the size you could learn on.

         Happy days!           PB

                                                                                                                                               

[William Morrison]

Castor oil is good for your bearings as it does an excellent job of coating the bearing.  Castor has a higher burn temperature so holds up better under harsh conditions.  Castor morfs into a longer molecule chain under temperature and pressure and becomes a better lubricant.  Castor will keep your engines running longer than any other lubricant.

 

But because Castor is not completely burned, it is expelled oil all over the airplane.  So it is a mess to clean up.  Castor  forms a surface varnish and in time coats the engine in brown caked on material.

 

And if an engine is stored in Castor, it will sieze up (but can be loosened up with heat and washed in methanol).

 

So I use a blend of Castor and synthetic oils.  A small amount of  Castor goes a long way.  So here in the US, it is more common to see blends of say 20% Castor to 80% synthetic for a total of 18% lubricant.  I often doctor my fuel up by adding a couple of ounces of Castor to the blend.

 

Cheers,

 

Chip

[William Morrison]

Posted by Malcolm Fisher on 15/02/2008 17:32:00:
Thanks for your comments Eric, but you haven't solved my dilemma. OS says use castor based fuel, most modern gurus including Steve Dorling and Brian Winch are totally against castor yet both have said "do what the manufacturer says"...

We had a bit of Brian Winch here in the colonies in Model Airplane Report, a highly respect magazine (but alas went broke).  He was out of touch then as he is now regarding the use of Castor. 

 

Granted using Castor is a continous and raging argument here but we do not enjoy the higher quality synthetic oils you chaps do.  So most of the gurus recommend a blend of 80% synthetic and 20% Castor.  Those that do use that blend seem never to have rusty bearings in either four or two stroke alcohol engines.  Those that do not use Castor must use after run oil and hope for the best.

 

Almost no one uses 100% Castor anymore, it is truly to messy.  And a little bit of Castor goes a long way in protecting the engine.

 

It is your engine, use what you want.  Methanol is methanol, not much you can do for it.  Adding Nitromethane helps it burn and thus makes the idle better and may give a little better top end.  But once you get past the 10% level, the benefits seem to taper off.  Again, some is good, a lot is a waste for money.  Yes, you get bragging rights but what is it worth to get them.

 

Cheers,

 

Chip

[Ernie]

Just smell the castor, and you will never use anything else

 

ernie 

[Aslan]

Coming in late on this thread ,so haven't read through the whole thing. Apologies if I repeat what has already been pointed out. Some points on Williams post. Both Castor and Synthetics do the job,i.e. keep the engine cool. Castor,however, is a little more forgiving if the engine is tuned on the lean side. Which should not happen in the first place.Nitro certainly helps Methanol burn, because it is an oxidizer, and therefore more oxygen more fuel burned, and so more power, and definitely beyond 10% in a big way, and vice versa. In fact more nitro = more pressure, and this can cause pre-detonation, to the point of having to add a head shim to lower the compression,using a cooler plug can help here also. The problem with Methanol is it's ability to draw moisture from the surrounding air (hygroscopic) Castor does not protect against this, and after run oil should be used no matter which oil is used. i don't use after run oil regularly myself, only  for storage reasons. Again just my slant on Williams opinion(without malice,of course).

[Supersooty]

Having been modelling for some 42 years now, I have read many times, listened to all the 'Experts' ('ex' is something that has been and 'spurt' is a drip under pressure!), it all comes down to price, value for money and personal preference.  My fuel of choice for all glowplug engines 2 and 4 stroke is 'Southern Modelcraft's' what I call 'Laser Ribena'.  If I remember rightly, the oil content is 17% ML70 and 2% castor (for the bearings).  Using this fuel in straight, 5% and 10% plus standard idle bar Taylor plugs I have never had an engine hiccup or failure for as long as I can remember.  All my engines run clean and have lasted for years.  I have never used after run oil, I hang all my fuselages up by the prop so that any corrosive residue, (when nitromethane burns it forms nitric acid) pools in the backplate and does not attack the bearing surfaces.  If I lay an engine up for any length of time I will inject an liberal dose of 3-in-one type of oil into the upper cylinder and into the crankshaft intake port.  I am not an 'expert' I am just a sport flyer who enjoys reliability. 

 

I hope this information is of value to somebody out there. 

 

 

[Alan Shipley]

Hi lads, no wonder Brian Winch pulls his hair out when you read some of this. Caster oil was the best 20 years ago but not now. Caster in a rotary valve engine is a big No No,  even Laser engine people tell you to use full synthetic now. Synthetic oil is not a bit better but its mile's better than caster. If you use the engine in race mode and lean the engine out  -no wonder you get problems.

Alan

Edited for tone

Edited By Tim Mackey - Administrator on 30/06/2010 09:37:35

[Former Member]

[This posting has been removed]