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Adding Oil

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Roger Dyke27/10/2018 17:04:39
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157 forum posts
6 photos

Hi All,

I have about 4 litres of fuel which consists of:-

9% synthetic oil

6% castor oil

5% nitro

80% methanol

I wish to increase the total oil content from 15% to 20%

What sort of oil can I add to the mix to increase the oil content?

Roger

Jon - Laser Engines27/10/2018 17:20:58
4496 forum posts
164 photos

is there a reason you want more oil? 15% is more than enough. In fact, with most engines you would be fine with just the 9% synthetic!

Peter Christy27/10/2018 18:28:55
1315 forum posts

Quite! The only reason many commercial fuels had 18% oil was because OS wouldn't accept warranty claims on engines that had been run on less. When the fuels I use was upped from 15% to 18%, all that happened was much more goo on the model!

--

Pete

Roger Dyke27/10/2018 18:37:16
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157 forum posts
6 photos

The engine in question is an Enya 15-III of about 1973 vintage when I purchased it new. It's in good condition and has had about 2 years in total run time. The reason for the request comes from the original instructions which states 20% castor oil. I understand that the engine has a steel piston and liner which is not the same as the more modern engines. I know that models do get very gluey with this amount of oil. I just want to be fair to the engine.

Roger

Don Fry27/10/2018 19:08:33
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3383 forum posts
40 photos

First, is the proposed fuel you wish to alter fresh, i.e. How long since it was a virgin, unopened tub of fuel. And your run time does not compute, 2 years, (2*365*24) is a lot of hours.

Manish Chandrayan27/10/2018 19:20:35
553 forum posts
65 photos
Since it's an older steel piston, my money would be in increasing the castor content in the fuel to get the oil to 20%.
Yes the model will get a good coat of oil, but the engine will be fine.
Roger Dyke27/10/2018 19:24:36
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157 forum posts
6 photos

Don,

The fuel is reasonably fresh (this year). In 1973 (approx.) I purchased the engine but it only did a couple of 5 minute flights.The two years represents the time it took me to learn to fly in 1994, plus about 12 months afterwards. It's not been used since until about two weeks ago when I re-joined a club. It's now had 4 flights in the last couple of weeks or so.

Roger

Edited By Roger Dyke on 27/10/2018 19:29:14

Roger Dyke27/10/2018 19:27:05
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157 forum posts
6 photos

Manish,

Have you any idea where would I obtain a small amount of suitable castor oil to add to the mix?

ASH.27/10/2018 19:27:32
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262 forum posts

Roger, it depends on what synthetic oil is already in the fuel. It could be ML70 or Klotz (US,very expensive). Both are available over here. Or you could just top up with a few % castor. I have no experience with steel pistons and liners but I would just run it with the fuel you have keeping an eye on the temp and smell. Is the engine run in?

brokenenglish27/10/2018 19:30:14
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396 forum posts
28 photos

Roger, To go back to your question. It's true that older engines do need more oil. I think you're right to go to at least 20%, and there are many forties and fifties vintage engines for which even that wouldn't be enough.

IMO you can use just about any good quality oil. Just decide whether you want to increase the synthetic or the castor content (or both), and mix accordingly.

In the past, I've used Castrol Racing 2-stroke oil (synthetic), sold in supermarkets for motocross, etc. I've also used Castrol GTX car engine oil which was very good, and the current version of that is synthetic.

I was lucky to acquire a good stock of Castrol M and, for most of my fuels, I'm now using a mixture of the Castrol M and the Racing 2-stroke mentioned above. Works fine.

In any case, the golden rule has to be don't use less oil than is specified by the engine manufacturer!

ASH.27/10/2018 19:30:52
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262 forum posts

Good Castor oil is available from Model Technics. Could be ordered to a local model shop if they sell their fuel.

Not all oils mix with Methanol.

Edited By ASH. on 27/10/2018 19:37:47

Jon - Laser Engines27/10/2018 19:31:25
4496 forum posts
164 photos
Posted by Roger Dyke on 27/10/2018 18:37:16:

The engine in question is an Enya 15-III of about 1973 vintage when I purchased it new. It's in good condition and has had about 2 years in total run time. The reason for the request comes from the original instructions which states 20% castor oil. I understand that the engine has a steel piston and liner which is not the same as the more modern engines. I know that models do get very gluey with this amount of oil. I just want to be fair to the engine.

Roger

I wouldnt worry personally. I have run old os's that demanded 20% castor using 15% synthetic and they have never been happier!

Manish Chandrayan27/10/2018 19:35:34
553 forum posts
65 photos
If you are ever in India, I could supply you with all you could carry back. Guess for now you will have to rely on UK suppliers
Manish Chandrayan27/10/2018 19:40:51
553 forum posts
65 photos
Long time back, during a field tenure in the deserts, did mix a small batch of diesel fuel with ether begged from the field hospital, kero from the kitchen, and Castrol two stroke oil from MT section. Engine ran ok, but I changed to standard mix with castor at the first available opportunity.
Roger Dyke27/10/2018 19:50:33
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157 forum posts
6 photos

Thanks for all your valued replies.

The engine is run in and runs very well. I just don't want to ruin it by operating it with the wrong mix.

Roger

ASH.27/10/2018 20:03:05
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262 forum posts

Then, to play it safe and have no worries -order a litre of quality Castor oil from Model Technics. It's also the cheapest option.

Roger Dyke27/10/2018 20:06:19
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157 forum posts
6 photos

Yes, I think that's probably the answer.

RC Plane Flyer27/10/2018 20:27:56
577 forum posts
22 photos

Hi Roger . I have no links with Model Shop Leeds but they have Model Technics Castor Oil available on their web pages

Roger Dyke27/10/2018 21:01:07
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157 forum posts
6 photos

Thank you for that. I have just ordered a litre from Wheelspin Models a few moments ago but thank you anyway.

Peter Christy27/10/2018 21:33:48
1315 forum posts

Roger, I would not put castor oil in *any* of my engines, and some of them are old enough to make your Enya look like a spring chicken!

Aside from some Cox .049s, my oldest engine is a Webra 61, which I bought new in 1968 (or maybe late 67 - its a long time ago!). That has been run exclusively on synthetic for many years, and is still hauling a large aerobatic model around today!

My fuel of choice is Bekra, from Model Technics, which contains a blend of Klotz and EDL. Although intended for helicopter use (where heat dissipation is a priority), it also makes a good general purpose fuel. I use "straight" (no nitro) in the Webra and the Super-Tigres I have, and 16% nitro in the Cox, OS and Irvines. I also use it on 4-strokes! All are spotlessly clean, inside and out, after many years of service.

All castor does is cause varnish to build up on the outside, making the engine look bad and restricting cooling, and on the inside, gumming up the works and again restricting heat flow.

A mix of synthetic and castor may reduce the varnish build up, but won't eliminate it. Castor is past its sell-by date!

Although my *personal* preference is Bekra, any good quality synthetic fuel will be infinitely preferable to castor, regardless of the age of the engine.

--

Pete

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