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Castor Oil

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ChrisH13/06/2017 22:52:18
22 forum posts

They say no question is a stupid question if you don't know the answer, so here's another question!

Is there any difference, or what is the difference, between Castor Oil that is used as an engine lub and castor oil that is used for cosmetic use as sold by health shops and chemists etc.?

Another way of putting the question is if I buy castor oil from the chemist/health shop is it OK to use as engine lub?!


Jon - Laser Engines13/06/2017 23:18:48
5077 forum posts
217 photos

There are many different grades of castor available but I would expect medicinal stuff to be pretty good quality. In the old days you could by paraffin from the petrol station, ether and castor from the chemist and then spend a slightly hazy afternoon mixing model diesel fuel before staggering off to fly.

If only it was that easy now.

Anyway, the big question for me is why on earth you would want to use castor as a lubricant in 2017. Its long dead, synthetic is better :P


Edited By Jon Harper - Laser Engines on 13/06/2017 23:18:57

Peter Miller14/06/2017 08:17:51
10511 forum posts
1246 photos
10 articles

Just as a point of interest I see that you can buy ether on EBay and it will be shipped by courier.

I wonder if anyone on the forum has bought any that way considering how hard it is to get hold of it by other means.

Cuban814/06/2017 08:47:38
2833 forum posts
1 photos

I echo Jon's question, why use castor these days? I was running 2% castor in the mix up to around ten years ago, but I only use fully synthetic oils now.

Model Technics and Southern Modelcraft products, but I have begun using Weston's Liquid Gold (secret oil content, but my simple tests put it at about 18% oil, perhaps slightly less) as Inwood's usually have it in stock and at under fifteen quid for a gallon of 5% nitro, it's a good deal and performs very well.

Edited By Cuban8 on 14/06/2017 08:48:35

geoff wise 114/06/2017 09:15:01
31 forum posts
23 photos

AP engines say you must use caster, cox say you must use caster, they say its for cooling, Den's models on the Isle of Wight is the cox king, he also has very small blind nuts with allen screws which are great for all sorts of jobs, worth giving him a look, small servos is another and a nice bloke with very good service, but of course we all know the real reason, the smell, ask captain slow (James May)

Geoff Forgot to say i get mine from barrets and may

Edited By geoff wise 1 on 14/06/2017 09:16:25

Braddock, VC14/06/2017 09:54:00
1640 forum posts
82 photos

I have to say that castor oil has one endearing property that synthetic oil cannot match, viz. it's an excellent laxative. face 23

TIM Shaw14/06/2017 09:55:04
166 forum posts
41 photos

IITC, the instructions with some of my old diesels, (Oliver or PAW?) specifically stated something like "Clinically pure, first pressing Castor oil" for mixing your own fuel.

I would imagine that is the sort of grade a pharmacist would have.

But I agree, why would you want to? I'm still running Duraglow 10, which has a castor content, but only because I had about 3 gallons of it when I stopped flying IC a few years ago.

Now I'm back into it I will be going for formula Irvine next, and then compare with Optifuel 10, unless I get sidetracked by something else at Weston Park.

Edited By TIM Shaw on 14/06/2017 09:55:32

Jon - Laser Engines14/06/2017 10:27:38
5077 forum posts
217 photos

Two stroke 'classic' diesels do work better with castor, but modern abc style engines would be fine with synthetic. All my Laser diesels run 15% synth without issue and they virtually drown on 20% castor.

My OS 15fp instructions state only use 20% castor but its happy as a clam on 15% synthetic as is a moki 180 a friend has. He is using the model technics laser 5 fuel and it works brilliantly.

Tim, i would suggest you skip the formula irvine fuel. its quite messy, especially the 10% flavour and still contains castor. I would recommend either Laser 5 or Techpower 5 from model technics. they are clean running fuels that work really well.

If the fuel is for a laser dont touch weston stuff as it is not compliant with our warranty specification.

Peter Miller14/06/2017 11:10:54
10511 forum posts
1246 photos
10 articles

I use Formula Irvine 10%.

Many years ago Clarence Lee suggested 2% Castor as an insurance against a lean run.

Mind you, when I wrote an article on Diesels for RCM Clarence Lee had to poke his nose in and revealed a total ignorance of the subject. Blaming the black sludge from a PAW on a lean run. How do you get a lean run on a diesel?

Martin Harris14/06/2017 11:54:53
9093 forum posts
224 photos

I have very little knowledge of "model diesel" operation (although of course, technically glows are a form of diesel) other than some control line models in my teens using DC Merlins and similar but I can't see why it's impossible to run one lean. I'd be interested to learn why this isn't possible?

Jon - Laser Engines14/06/2017 12:21:02
5077 forum posts
217 photos
Posted by Peter Miller on 14/06/2017 11:10:54:

Many years ago

The above pretty much sums up the whole debate about fuels and oils. So much of what modellers believe is the right thing to do is based upon decades old information/practices which are no longer relevant.

Its not a criticism of anyone or a personal attack, its just that many of us have been doing things a certain way for forever and arent always aware that things have changed, and even when told it often causes heated debate when it should really just be taken at face value

Nigel R14/06/2017 14:35:37
3403 forum posts
524 photos

Jon, I understand you're intending on changing to a 10% minimum recommendation for Lasers?

Is it "close enough" to use a mix of a gallon of one of MT's 18% oil blends + gallon straight methanol?

Jon - Laser Engines14/06/2017 15:21:03
5077 forum posts
217 photos

10% oil have proven very successful for our engines and we do have some guys mixing a gallon of 10% nitro 18 or 20% oil fuel with a gallon of methanol and apparently not having any issues.

I have no doubt that 10% oil is satisfactory as my 100 flew all last year on 4% and our petrol prototypes use less than that. 10% should be totally safe assuming you use decent oil and not chip fat

TIM Shaw14/06/2017 18:29:44
166 forum posts
41 photos

Thanks for the advice John, sadly no Lasers for me.

I am something of a diehard 2 stroke fan, with a liking for Thunder Tiger PRO and OS engines from a few years ag, although I confess I have a couple of the AXs which I like a lot.

And I have the formula Irvine in stock.....

ChrisH14/06/2017 18:35:44
22 forum posts

Thanks for the replies Guys.

At present I don't use anything as I haven't got a running engine! However, the query arose in my mind of the use of an oil to 'wet' a dry engine before running, and perhaps after when laying up an engine for a period, and as a lot of glow fuels seem to have some % of castor oil it seems a pretty safe oil to squirt around, going back a long way. Then it seemed that it wasn't as available in chemists as it used to be, or maybe I'm just looking in the wrong place.

It wasn't a 'should I use castor oil instead of synthetic' question, more a 'could I use....' type question, pure curiosity! But thanks for the replies, very interesting.


Martin Harris14/06/2017 18:45:26
9093 forum posts
224 photos

I use air tool oil for lubricating engines when I rebuild them or lay them up for any time.

Steve Hargreaves - Moderator14/06/2017 20:11:20
6730 forum posts
191 photos

You could use some "After Run" oil to initially lubricate a "dry" engine Chris....available in small quantities (250ml or so). Be careful not to put to much in though lest the engine should experience a hydraulic lock when you try starting it again.

I agree with most of the other chaps in that castor oil has long been surpassed by modern oils....thumbs up

John Bisset14/06/2017 21:21:31
204 forum posts

I'd agree with Braddock VC (Ah - the old stories from many years ago) that castor oil is an excellent laxative, That was why some early aviators had digestive problems...

Castor oil does form a glaze on metal surfaces at high temperatures. I recall that being viewed as a benefit for some model engine use, to improve sealing. So, maybe not entirely superseded by synthetics.

Ian Jones14/06/2017 23:54:44
3219 forum posts
1397 photos
Posted by Steve Hargreaves - Moderator on 14/06/2017 20:11:20:

You could use some "After Run" oil to initially lubricate a "dry" engine Chris....available in small quantities (250ml or so). Be careful not to put to much in though lest the engine should experience a hydraulic lock when you try starting it again.

I agree with most of the other chaps in that castor oil has long been surpassed by modern oils....thumbs up

Yup, that's what I use. Since I always use it at the end of every flying session (except on the odd electric only day wink 2), then I always have it available. If I'm not going to use an engine for a while I just put in a few extra drops. Before using the engine again it'as a quick check for hydrualic lock, fuel up and they nearly always start first time. Had my first bearing failure a few months ago after 14 years of using this method.

G194015/06/2017 00:10:50
3523 forum posts
1 photos

I've been following model aircraft forums for a few years now and the castor boon or not dilemma comes up at regular intervals. I used to use it inadvertently when I used Dura and Dynaglo fuels but the only time I ever used it on purpose was when I added a few drops of Castrol 'R' to the fuel tank of my 1932 Scott TT Replica motor cycle, just for the heavenly smell


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