Adding Oil

[Roger Dyke]

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 H]

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 Christy]

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 Dyke]

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 Fry]

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 Chandrayan]

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 Dyke]

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 Dyke]

Manish,

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

[ASH.]

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?

[brokenenglish]

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.]

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 H]

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 Chandrayan]

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 Chandrayan]

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 Dyke]

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.]

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 Dyke]

Yes, I think that's probably the answer.

[Keith Berriman]

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

[Roger Dyke]

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

[Peter Christy]

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

[Roger Dyke]

Hi Pete,

Thanks for the post. I am very much okay with the mechanics of engines but very weak on fuel preparations. I know all about castor varnish from all my other engines. I am only going by manufacturers recommendations which I thought was a good place to start. Your experience with purely synthetics is valuable and might be a consideration for me in the future. Thank you for that.

[Jon H]

im with Peter on this one. synthetic oils are far better than they were and frankly there is no advantage to running castor. The bekra fuel is fine, model technics laser 5 and techpower 5 would also be good choices.

[Former Member]

[This posting has been removed]

[brokenenglish]

Posted by Andrew Ray on 28/10/2018 06:51:07:

Roger, don’t forger the manufacture’s recommendation for oil is 45 years out of date.

I disagree, it's the engine technology that's changed.

I run a lot of old engines, and they really do need the oil proportions specified at the time.

[Denis Watkins]

Posted by brokenenglish on 28/10/2018 07:45:18:

Posted by Andrew Ray on 28/10/2018 06:51:07:

Roger, don’t forger the manufacture’s recommendation for oil is 45 years out of date.

I disagree, it's the engine technology that's changed.

I run a lot of old engines, and they really do need the oil proportions specified at the time.

Run the % oil if pushed to do so

But don't put Castor in the mix

Synthetic oil has evolved to suit our needs,