Synthetic instead of caster oil?

[John Wagg]

I have always used caster based fuels. Both 2 stroke and 4. Just ordered some Laser 5% which is synthetic. Now on full size engines it was considered not good to change oil types (mineral to synthetic). Is there any problems switching between lube' oils on my engines?

[Jon H]

Posted by John Wagg on 15/01/2020 20:33:07:

I have always used caster based fuels. Both 2 stroke and 4. Just ordered some Laser 5% which is synthetic. Now on full size engines it was considered not good to change oil types (mineral to synthetic). Is there any problems switching between lube' oils on my engines?

nope, use the Laser 5 and never touch castor again!

[Ronaldo]

As Jon says ... I also only ever use synthetic now, much cleaner engines and models

[Stephen Smith 14]

Only problems you will have are better running, cleaner engine, better starting, and less wear, other than that pretty much the same

[Former Member]

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[Martin Harris - Moderator]

Is it that bad? I believe Model Technics Laser fuel contains ML70 and so does my usual supplier's, Southern Modelcraft. Jon seems to have no problem continuing with Neil Tidey's endorsement of Model Technics fuel.

[John Wagg]

Thank's all for the input.

I will still use up my oldish fuel but will be using the Laser on my 4 strokes to start with. Hopefully the weather will improve soon so I can quickly get rid of the caster stuff.

[Jon H]

Posted by Jason Channing on 15/01/2020 21:14:47:

I always use synthetic but I use the klotz oils which is certainly more forgiving than ML70 which by todays standards is quite old technology and things have improved a long way over 35 years since ml70 was first produced. Would I use ml70 in aYS or other good engine ...NO

ML70 is fine. It got a great deal of hate in the early days but things have come a long way since then. The oil itself has improved and its the oil used in the laser 5 fuel we recommend for everything. I have run ML70 down as low as 5% in testing and we are looking to introduce a 7% ml70 fuel for laser engines as soon as we can get it all sorted.

All of my own engines, be they laser, enya, os etc all run on the laser 5 fuel and they are all very happy.

[Cuban8]

Posted by John Wagg on 15/01/2020 22:40:38:

Thank's all for the input.

I will still use up my oldish fuel but will be using the Laser on my 4 strokes to start with. Hopefully the weather will improve soon so I can quickly get rid of the caster stuff.

Best used a first class weedkiller or bonfire starter........only kidding!

[Peter Christy]

I run all my engines - from Cox .049s to 4-strokes - on Model Technics Bekra fuel. The main oil constituent is Klotz, no castor whatsoever, and no problems.

Although sold as a helicopter fuel, it works fine in all my engines, ancient and modern! Helicopters generally run hotter than fixed wing, so if the fuel will work in a heli, it will have no problems in a fixed wing!

--

Pete

[Brian Cooper]

Castor oil is what you give to children who you don't like very much.

We used castor oil in our engines in the 1960s, but the game has moved on and I certainly wouldn't put the wretched stuff into a model engine nowadays.

[J D 8]

Only place I use castor is in my old DC, Mills, Frog diesel engines.

OH and last year I put some in my old lawnmower. Lovely smell that reminded me of my Grasstrack racing day's

[ASH.]

Posted by Jason Channing on 15/01/2020 21:14:47:

I always use synthetic but I use the klotz oils which is certainly more forgiving than ML70 which by todays standards is quite old technology and things have improved a long way over 35 years since ml70 was first produced. Would I use ml70 in aYS or other good engine ...NO

 

Thanks Jason, I thought I was the only one!.. I have seen a marked difference between the two oils. The Klotz makes my 4st engines run so much smoother. It's got to be down to quality., no other explanation.

Now, if MT made a ready mixed 10% Klotz, 5% Nitro at a decent price I would go for it - and stick to it.

 

Edited By ASH. on 18/01/2020 08:39:09

[Jon H]

Posted by ASH. on 18/01/2020 08:34:30:

Posted by Jason Channing on 15/01/2020 21:14:47:

I always use synthetic but I use the klotz oils which is certainly more forgiving than ML70 which by todays standards is quite old technology and things have improved a long way over 35 years since ml70 was first produced. Would I use ml70 in aYS or other good engine ...NO

Thanks Jason, I thought I was the only one!.. I have seen a marked difference between the two oils. The Klotz makes my 4st engines run so much smoother. It's got to be down to quality., no other explanation.

Now, if MT made a ready mixed 10% Klotz, 5% Nitro at a decent price I would go for it - and stick to it.

Edited By ASH. on 18/01/2020 08:39:09

I take it you didnt see my post which explained there is nothing wrong with ML70?

Any difference between the two oils would only apparent if you measured things like wear on components, film strength and all that. As the oil contributes nothing to the combustion it has no effect on how smooth an engine will run.

I say two oils, but so far the only comparison has been between one oil and one manufacturer. Klotz make a number of different oils and some, like super techniplate, are very much inferior due their castor oil content.

When working with model technics on the low oil fuel we now have there was a discussion about which oil would offer the best performance and the end result was sticking to ML70 as each oil performs more or less the same as the others.

[Peter Christy]

Posted by Jon - Laser Engines on 18/01/2020 11:00:06:

I say two oils, but so far the only comparison has been between one oil and one manufacturer. Klotz make a number of different oils and some, like super techniplate, are very much inferior due their castor oil content.

Quite correct, which is why Bekra uses plain Techniplate, which contains no castor.

IIRC, it also contains small amount of other synthetics as well, as each synthetic has a working temperature range. I was told that these small amounts of other synthetics (may well be ML70) provide some protection outside of Klotz's range - for example during a prolonged lean run.

Certainly, my experience had been that with standard size motors (ie: up to .90 size), nothing compares with Bekra. Clearly larger motors may need less oil, and for bigger engines I have no direct experience.

--

Pete

[Jon H]

Yea bekra is ok and the techniplate oil it uses is just fine. I recommend it to our international customers who cannot find ML70.

The lean run protection is a constant theme in all oil discussions and its another piece of folk lore as engines generally will not run if they are too lean so its just not possible to have a prolonged lean run in most cases. If an engine is too lean rpm will drop and temperature will rise. Within a very short time the engine will simply stop and this will occur long before the engine gets hot enough to burn off the oil.

'Lean' runs are normally just simple overheating caused by poor cooling and/or the engine suffers a lean cut in flight due to poor tank placement and a change in fuel head as the tank is drained causing a leaning of the mixture.

[Nigel R]

But. My understanding - perhaps wrong or oversimplified- too lean also means an advance in the ignition leading ultimately leading to pre detonation and high temperature?

[Jon H]

Posted by Nigel R on 18/01/2020 13:09:22:

But. My understanding - perhaps wrong or oversimplified- too lean also means an advance in the ignition leading ultimately leading to pre detonation and high temperature?

Too lean is a condition where there is insufficient fuel to maintain combustion. In most engines, this is apparent due to a sudden and significant drop in rpm. We notice this when tuning as the revs sag, but then return to normal once we dial it back a click or two. If the engine is maintaining peak RPM it is not, strictly speaking, too lean.

Knocking can occur if engine load or temperature is too high as it advances the ignition more than the engine can handle. Tuning may be correct, but it will still knock due to one of these two issues and its normally heat that does it.

As an example, take an engine and tune it for max rpm. Then block off half its cooling air and wait. Most likely it will run for a while, then begin to slow down/knock before it either stops or spits the propeller off. In this case, the engine was never run lean and yet it knocked itself out due to excessive temperature and this is the 'too lean' failure we always see in models due to insufficient cooling.

[paul d]

Jon, I must pick you up on a couple of points, you say the oil contributes nothing to combustion, of course it does! it's present in the combustion chamber when ignition takes place and a proportion of it burns which takes me to my second point.

You also say oils lean run protection properties is folk lore, you fail to mention the secondary function of the oil, it dissipates heat, oil that doesn't get burnt exits the exhaust taking heat away.

The slowing/stopping/ prop throwing has nothing to do with there being insufficient fuel to maintain combustion it's due to the engine suffering a partial seizure.

I do seem to remember reading of your trouble with a paw 60 diesel and your attempt at a cure with poor running, you drilled a hole in the cylinder head when it was quiet obvious it had a worn bore allowing the products of combustion past the contra piston!

I know it sounds like I'm "having a pop", I'm not I'm just giving you my opinion having spent 25 years working in F1, now those engines do operate at the limits of what's possible when it comes to cooling and lubricating.

As a aside and it may be of interest to some but 'we' once used a modified laser engine as a air pump back in Ayrton Sennas days with the Honda engine ( you may need to ask Neil about that!).

[paul d]

Sorry forgot to add: In response to John's original post, just ask the engineers at old warden to abandon castor in favour of modern synthetics in there vintage rotarys etc....castor still has a place imho..... tin hat firmly applied.....

[Don Fry]

Posted by paul d on 18/01/2020 20:20:42:

Sorry forgot to add: In response to John's original post, just ask the engineers at old warden to abandon castor in favour of modern synthetics in there vintage rotarys etc....castor still has a place imho..... tin hat firmly applied.....

Tolerances of half an inch perhaps, gum has uses.

[paul d]

Don, having worked extensively on the clerget radial fitted to the Brooklands museums sopwith Camel ( replica airframe, original engine) amongst many other full size engines I can assure you the tolerances are extremely tight..... A very interesting subject for a sensible discussion.

[Don Fry]

Sorry Paul, being facetious. But I still can't see the relevance of 100 year old oil and engine technology, on machines that got through the thick end of a gallon of oil an hour at half throttle. Might as well start a lecture on the efficiencies of biplane wing arrangements and ask modern designers to take note.

[paul d]

Totally relevant Don....'our' engines like the rotarys of yesteryear both relie on total loss lubrication..enjoy your Sunday

[Former Member]

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