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Author Topic: How much castor oil to protect & how much Syn to keep clean?  (Read 419 times)

Offline Dennis Toth

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How much castor oil to protect & how much Syn to keep clean?
« on: December 31, 2019, 09:01:17 AM »
Guys,
Happy New Year to all !!

Getting ready to start the roaring, roaring 2020's season and wanted to get a few thoughts on fuel mix. How much is the minimum % amount of castor oil to give protection and conversely how much is the minimum % of Syn oil to keep the engine clean? I know castor has the unique property of flowing toward the hot spot and Syn oil is a good detergent for varnish. In the older iron/iron engines castor is also part of the cooling system but does varnish up and require some sort of clean out. Using Syn oil keep the varnish away which helps with mufflered engines and also seems OK in ABC engines. Question is how much of each is really needed?

Best,    DennisT


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Online Lauri Malila

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Re: How much castor oil to protect & how much Syn to keep clean?
« Reply #1 on: December 31, 2019, 09:43:27 AM »
It depends on engine type, castor type and type of synthetic oil.
For example a good Retro .60 needs only 5% of synthetic to keep inside of engine clean. That's how it runs the best, but there will be carbon buildup inside the muffler. The DR.76 instead, allowed max. 5% of castor in mix to keep places clean. There are certain synthetic oils, like AeroSave, that clean the engine much better but for some reason Retro did not run well with it.
With piped engines I have allways used 11/11% mix, and all was allways very clean. I doubt that increasing castor % to maximum tolerable will improve the running quality of modern engines.
At the moment we have learned from F2C team racing engines, that only 1-2% of good castor is enough to get most benefits of it. So I use 2% of Castor #927 and 18% Klotz #189 low viscosity synthetic oil with quite perfect results. But in general, I would not recommend the low visvosity oils. L

Online Brett Buck

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Re: How much castor oil to protect & how much Syn to keep clean?
« Reply #2 on: December 31, 2019, 11:06:12 AM »

Getting ready to start the roaring, roaring 2020's season and wanted to get a few thoughts on fuel mix. How much is the minimum % amount of castor oil to give protection and conversely how much is the minimum % of Syn oil to keep the engine clean? I know castor has the unique property of flowing toward the hot spot and Syn oil is a good detergent for varnish. In the older iron/iron engines castor is also part of the cooling system but does varnish up and require some sort of clean out. Using Syn oil keep the varnish away which helps with mufflered engines and also seems OK in ABC engines. Question is how much of each is really needed?

  I would avoid more than about 5% castor in any modern engine. Even the difference between 11/11 and 5/17 is quite significant in terms of varnish buildup.

   An interesting thing when you switch - it takes maybe *a gallon* or so of running to get the full effect. Right away, the run difference will be obvious, but it keeps changing for about 20 flights until the level of varnishing stabilizes (more varnish or less varnish).

    Brett

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Re: How much castor oil to protect & how much Syn to keep clean?
« Reply #3 on: December 31, 2019, 11:11:55 AM »
Dennis, I run everything 46 size and below with 10% nitro 10% castor 10% Klotz Original Techniplate 70% methanol except 1/2a where I run 20% nitro and 20% castor. If I had bigger engines I'd run them with more or almost all synthetic. The smaller the engine the cooler it runs so the big engines coke up more than 1/2a. It also depends if your plane is over powered where you have to de tune the engine and run flat rich or if you have big plane little engine going for higher rpm and a 2 stroke break. Heat burns castor so plan your fuel accordingly. 


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Offline RandySmith

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Re: How much castor oil to protect & how much Syn to keep clean?
« Reply #4 on: December 31, 2019, 11:26:53 AM »
Guys,
Happy New Year to all !!

Getting ready to start the roaring, roaring 2020's season and wanted to get a few thoughts on fuel mix. How much is the minimum % amount of castor oil to give protection and conversely how much is the minimum % of Syn oil to keep the engine clean? I know castor has the unique property of flowing toward the hot spot and Syn oil is a good detergent for varnish. In the older iron/iron engines castor is also part of the cooling system but does varnish up and require some sort of clean out. Using Syn oil keep the varnish away which helps with mufflered engines and also seems OK in ABC engines. Question is how much of each is really needed?

Best,    DennisT

Dennis  that will  vary a lot,  Read the  fuel article  I wrote  pinned at the top of this engine forum

Randy

Offline Dave Hull

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Re: How much castor oil to protect & how much Syn to keep clean?
« Reply #5 on: December 31, 2019, 06:36:12 PM »
Perhaps a clarification to Lauri's comment?

If he is referring to Maxima 927 oil, be aware that it is only 50% to 70% castor. The balance is a mix of synthetic oils. The actual mix is proprietary, so they are not going to be more specific. Thus, if you used 2% Maxima 927 in your fuel mix, you actually are likely to have only about 1% castor.

One other thing to keep in mind. Lauri notes that in racing diesels, some teams are using a very small amount of castor. However, I believe that kerosene/paraffin has a higher lubricity than methanol, which might enable them to run with less than a glow engine. Also, their metallurgy is as good as it gets. Not true of most sport engines, and certainly not older stunt engines.

Dave

PS--As a related comment, the addition of small percentages of ethanol to gasoline is reported to significantly reduce the fuel lubricity. And, the high temperature cracking used to make the Ultra Low Sulfur diesel fuels also reduces the lubricity. So much so, that all of that fuel now needs additives to avoid premature wear of fuel pumps and injectors.

Online Lauri Malila

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Re: How much castor oil to protect & how much Syn to keep clean?
« Reply #6 on: January 01, 2020, 03:20:52 AM »
Good points, Dave.
But remember also that we use about twice as much oil than in team racing, I guess that evens out the lubrifying properties of other fuel ingredients. My point is mainly how little castor is needed to improve the oil film strenght in high pressure contact points.
Also, regarding our experiences with ideal oil percentages for Retro engines, also the Motul synthetic oil we use is a blend, so in fact we have no idea of the actual castor % 🙃.
L

Offline PaulGibeault

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Re: How much castor oil to protect & how much Syn to keep clean?
« Reply #7 on: February 09, 2020, 02:30:35 PM »
Right from a conversation I had with the late Bill Wisniewski, 3 parts synthetic oil to 1 part castor oil was his recommendation.  SO... 5% castor with 15% synthetic. The beauty of such a blend is that it remains homogeneous in the 65% nitromethane blend fuel that I use in my old metallurgy iron/steel piston cylinder engines.  Bill also mentioned that K&B's all synthetic oil fuels still contained 2% castor oil. At the time, Bill did not trust fuels with 100% synthetic oil at least for the general user.
 
So, to answer your exact question: At least 2% and not more than 5% castor oil is required to protect your piston/cylinder under the harshest competition conditions. 

BTW, in another conversation with the Klotz Oil technical rep at the 1999 AMA Nats was that a combination castor/synthetic blend yields an oil package with properties exceeding that of either oil used separately.  He did not know at the time that his preferred Benol (castor oil) product could be used with 65% nitro if it was mixed 5% with a synthetic oil which acted as a stabilizer which then allowed the whole mixture to stay in solution.

I hope this helps.

Cheers,

Paul G.

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Re: How much castor oil to protect & how much Syn to keep clean?
« Reply #8 on: February 09, 2020, 06:42:15 PM »
In my racing experience there is no combo of castor/synthetic that will do both max protection and stay clean, you choose one or the other so, of course 20% castor when allowed. Sport/stunt is another matter.

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Offline Air Ministry .

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Re: How much castor oil to protect & how much Syn to keep clean?
« Reply #9 on: February 09, 2020, 09:11:07 PM »
Just stripped anothe FP 40 . ( GP MANUM , actually )

the  useuall oxidation on the crank web & STUCK WRISTPIN in ROD .

How Unusual ,  LL~ :P

Thinking FLUSHING with methanol / metholated spirits , post flying . Preferably while still warm .
oiling maybe with the sewing machine oil , are as likely , or more , to prevent ' problems ' .

Even flash specialist engines get the rod - pin glued , and races rotted , stored with nitro residue .

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Id think 20 % Syn.'d be plenty to de carbon ' as you go ' ,

Generally use 3 % syn , 20 % Castor for sucklike . Some used REDEX in years gone by , particularly the Diesel team racers . just a few % .


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