DarZeelon

Hi Jan,


Now you're talking! It is true that none of the European synthetic model oils are simply not imported into the USA...
Maybe to protect the local petroleum industry...

As to lubricity and corrosion, I am sure these oils are as protective to the engine as is castor oil.

But... what about heat?

Castor oil has a flash point of 520-560°F (271-293°C). What can Motul and Sachs offer in this respect?


I don't think any of them come even close...


For a very careful user that never mal-adjusts his engine, it might not seem to matter, but could there be an immunity from making mistakes!?

yallaair

I've seen this argument a couple of times, but from my own experience this is not a issue for a synth fuel containing 15% oil or more. The past 10 years I have leaned out my engines several times. Even so lean that the glow plugs get busted. But no sign of oil film failure. Maybe this has to do with the cold climate, ambient temp is rarely above 23 deg.C (72degF).

asmund

Plus we try not to run our engines much above 500 deg [sm=lol.gif]
castor have always been good to me and so has synth. But lately it has become very difficult to even get fuel containing castor around here, and I have no reason to miss it either, ok the nice smelling smoke but that`s it

asmund

My MVVS 49 have not tasted a single drop of castor for several gallons now and it runs fantastic. Strong compression and really powerful. I have read that this engine almost will not run if not fed castor oil in large amounts Well mine really loves 15% of EUROPEAN synth oil (don`t know exactly which, the fuel is from France)

DarZeelon

Asmund,


My experience and therefore my recommendations (as well as the MVVS warranty requirements), are that a good amount of castor oil is necessary.

With 6% castor oil and 9% EDL synthetic (Model Technics Duraglow), this engine is a proven 'dog'... Adding 5% more castor oil made it a very submissive 'puppy'.

asmund

Hmmm, mine tachs 14300 rpm on APC 12-4 on 0% nitro and 15% synth. Today when I maidened my Faschination 40 it tached 13400 rpm on a JXF 11-6, ambient temp was -1 deg Celsius so it was freesing and I didn`t tweak it 100% due to cold fingers. Hardly a dog and it blows all OS engines around here of similar size completely away even though they run 15% nitro.
I can`t really complain and as long as it performs like this, what is there to miss. I have to really struggle to get castor fuel anyway and have it shipped from far away (we all know how cheap it is to have Hasmat shipped)


That was actually a JXF 11-7 at 13400 rpm and NOT an 11-6, I flew it again today in freezing temperature and got the same reading, and great performance

jaka

Hi!
Dar ! Being a pylonracer for many years I know that Castor oil can stand heat much better than any synthetic oil. This is a fact! But in real life the modern synthetic oils we have over here in Europe seem to funtion well too , and that even in temperatures above 30 degrees.
centigrade.

Dar! The MVVS oil recommandation is just a recommandation.It doesn't mean it is written in stone! When you have experience you know that there are other oils that work well too. But what MVVS do is to take no riskts so they say: "Use Castor oil" because this has worked for 50 years or more and will work now as well. That is true of course but
today we have supperior synthetic oils that work better soo Why not use them?
Haven't seen an engine that worked bad due to low oil percentage myself.

DarZeelon

Asmund,


Castor oil is not classified as a flammable, so I don't think HazMat applies...
Even 50/50 oil mix with nitro is not HazMat applicable, as far as I know.

asmund

Yes I know, I was thinking of premixed fuel containing castor. I could order castor oil and add to my fuel (still quite expensive at 20$ pr liter) but I don`t care to. My 49 has burned maybe 6 gallons of synth only since break in with castor oil precent and is performing GREAT. I expect not to be able to wear it out in many many years, and if so, a new setup is cheap. For what I`ll have to pay for a gallon of castor I can get a complete new set up I`ll stick with my readily available synth only fuel[8D]

asmund

Dar, maybe you should order yourself a liter or two of our European oils (Motul or Graupner Aerosave/synth) and give it a go
I think you would be pleased

DarZeelon

Asmund,


I have and I use Cooper Fuels Ester based synthetic oil, in a mix with castor oil.

If I had to buy Sachs oil, I would have to leave this hobby because of its very high expense...

gkamysz

My Feedback: (19)

Motul Micro is scarcely available in the US. The only place I found that has it is www.performanceoilstore.com

asmund

Yes I know, around here everything is very expensive. I see that it is possible to get a whole case of 30% fuel for rc-cars for 90$ in the US. Here in Norway I get ONE gallon of that stuff for the same amount of money[:@]
As a rule I always get whatever fuel for my purpose I can get for the best price. I don`t think there are any really bad fuels to be had around here anyway.
Maybe the next time I will shop any large amount of aero fuel it will contain some castor, price will decide. There are some Synt/cast blends to be had and if it is cheaper than the synt only I run now, I will get the blend next time I shop fuel. I really have nothing against a little castor in my fuel. Happy new year

yallaair

I see that there are some guys saying that there is a difference between US and European oils. The local brand I tested vs WilCat fuels, are using the same type oil: Klotz. So the only difference between the fuels is the oil percentage. So the conclusion I draw, is that lower oil percentage gives more power. If there is a difference, it should be quite easy to figure out by checking the viscosity grade, boiling point and flame point. To my knowledge, oil used in this test has a viscosity of 18cSt@100 degC.

Marcol

I'm with you on this one Jaka,

I run all my glow engines on 10% Prosynth 2000. This uses Aerosave as its lubricant and like you my engines are like new inside and out. I have been using this fuel for at least 6 years in everything from an OS 10LA to a Laser 240 V Twin.

The great thing is that after a days flying you just run the motor dry and a quick wipe down of the airframe and you put the plane away ready for the next time. No after run oil needed and no gooey castor gunge to contend with.

Never do a de coke. Never replaced a bearing since using Prosynth

XJet

We've had several occasions when people have run their engines (accidentally) very lean. You could hear them sagging on uplines and when they landed they had blown glowplugs.

Despite this "punishment", we've not experienced any failures, piston-scuffing, rod-wear or other damage as a result -- despite the low oil ratios we're running. Was it thanks to the very few percent of castor in the fuel? Or was it that the hi-quality synth didn't just evaporate but actually continued to provide the necessary protection.

Just how hot does the piston/liner interface of a model engine get when run really lean?

One thing I have observed is that even though very good synthetics will flash to vapor at a lower temperature than castor (which simply polymerizes), this phase change absorbs a huge amount of heat energy. So it could be argued that a synth oil will actuall *cool* the engine as it vaporizes whereas castor does not.

This is the kind of stuff for which we need some serious science rather than anecdotal evidence.

gkamysz

My Feedback: (19)

I read something that said upper cylinders in competition two stroke model engine run near 250°C, in the model, in the air. This was dated around the late 70's.

liquid_TR

Well, its not always the tuning to blame if something goes wrong. Ive been using Cool Power (which supposed to be a good quality fuel) for a long period of time without problems.

But my friends 46AX had an unfortunate lean run in the air.

I had tuned his engine before take-off with a rich enough mixture for protection, and he was flying the seagull arising star trainer with a buddy cable - master control on my side. Well.. at one point the muffler back-pressure tube came off the nipple while he was crusing at half throttle. Engine immediately started sagging. From a long distance, and the actual control on my friends stick - I thought he throttled down against the wind. When I told him to go full throttle, I saw with the corner of my eye that he was already at full throttle. I immediately released the trainer switch, gained control and throttled down. Made a very acrobatic turn to emergency land the plane. And I did. As soon as the wheels touched the ground the 46AX flamed out. Tried to turn the prop: it was stiff.. Oh dear.. This whole thing, from backpressure failure to landing the plane, took approx. of 15-20 seconds.

After we let it to cool down, we tried to start it again with a rich setting. It fired with some persuasion. I ran it for a minute, then shut it down to check the compression. It was back with smooth roll!! But later we found out all the pinch was gone. Its now MUCH harder to start it but when it does start eventually, it runs like a monster. (he actually said he probably had a couple of lean-side runs while I was away)

It not always the engine I care about, It the airframe. Now we both add some pure castor to our syth oil fuels for good measure.

Until the day those slick, high quality syth oil comes around where I live, I will be adding pure castor to my fuels. Maybe after that in small %s as well.

yallaair

This can indeed be plausible. Maybe also the reason why castor is producing more smoke than synth oil. The very high flame temperature in the combustion chamber WILL make some of the castor droplets polymerize. Hence, this causes smoke and maybe also carbon. But some of the droplets from a synth oil will evaporate and since tis takes about 500-1000 kJ/Kg of energy, the small drop in temperature may cause the remaining oil stay just within the limit of accepted viscosity. I don't think this is measurable on the outside of the engine, but it is theory.

Then the clue is to have sufficient amount of synth oil in case of leanruns. A local brand offers 12% synth oil mix. Have not heard any bad things about this fuel. The name of the oil producer is not stated, but they says it's coming from Germany.