High oil content

[Brett Buck]

they have 2 10% airplane fuels with 18% oil one all synthetic and one half syn and half castor,i dont imagine you would need any castor with the RO jett engines

  I think the all-synthetic is Powermaster "Heli", not Powermaster "Air".  Or, I am just unaware of it.

    Brett

[Reptoid]

I think the all-synthetic is Powermaster "Heli", not Powermaster "Air".  Or, I am just unaware of it.

    Brett

That is correct. 18% Air is 18% total oil (20% of that is castor/80% of that is synthetic) 

[doug coursey]

I think the all-synthetic is Powermaster "Heli", not Powermaster "Air".  Or, I am just unaware of it.

    Brett

I WILL CHECK WHEN I GET HOME the half and half is airplane

[Brett Buck]

That is correct. 18% Air is 18% total oil (20% of that is castor/80% of that is synthetic) 

  I think it is 5/12, at least when we asked them about 20 years ago. Interestingly - my engine will not run properly on 20% 50/50 oil, it misfires in inside loops.

   Brett

[bob whitney]

what oil did K&B use in their speed fuel  RAD

[Dave Harmon]

Always an interesting subject. I really enjoy hearing others experience with fuels.

Having flown Pattern a LOT with YS 170 and larger 4 stroke engines, they always ran a LOT better with Cool Power Heli 30% nitro.
Of course the nitro was needed to get the stump pulling torque on those large props but the REAL thing was the oil content and type.
This was pretty well known in that crowd for years.

Then later, I started up again with control line with engines that were not ever imagined long ago.
So what am I gonna do with all this Heli 30% fuel...cases of it?
I went back to mixing my own stuff...in researching what to do I read Randy's comments about boiling off fuel to determine the oil content....but I didn't use a hot plate.

I put 8oz in a Pyrex cup then put it in a crockpot. Filled up the pot with water higher than the fuel in the cup, then put the pot on high.
This boils off everything but the oil in the Pyrex cup.
I determine when it is all gone by sniffing it...when it don't bite my nose...the nitro and alky are gone...the oil remains.

For this fuel....CP Heli 30%, 8oz boils off to 1oz...or 12% oil in that fuel.
This is in spite of the nonsense oil content claims on the Morgan website.
Reality always bites.
Then I crank the calculator and add Klotz KL-198 and balance alky to make 18% oil content fuel to use in the Rojetts.

I flew today with Joe and Tim and of course the 67 just snoozes right along never missing a beat.
For guys that have access to high nitro fuels....like at a hobby shop or Hobby town, you can buy 1 gallon of CP 30% heli and easily do what I do and have good fuel at a decent price. You won't need more nitro...just get KL-198 off ebay and find some alky and mix it up.
The trick is finding out how much oil is in the base fuel.

I get 4 gallons of 10% nitro, 18% oil c/l fuel from 1 gallon of CP 30% heli fuel.
Pretty cheap if you ask me and and at 5 oz or so per flight...1 gallon of Cool Power Heli 30% lasts a long time.
Much better than 24 oz per flight of full strength CP 30% on those 4 strokes.
Flying c/l is almost free...
Nuttin tuit.

[doug coursey]

if we are talking about VP Powermaster fuel this is their list for 10% airplane
An ultra-clean burning fuel containing a 17% castor/synthetic oil blend built for scale R/C aircraft stability and easy tuning. A one-quart bottle retails for $13.29 at Absolute Hobbyz. [1] (https://www.google.com/search?q=product&prds=pvt:hg,productid:13068028271145146948,catalogid:11689442344757700136,gpcid:1402487218110575479,mid:576462800908321009&ibp=oshop)
heres another 10 rc racing airplane fuel description ................VP's 10% Air features a premium oil package consisting of 80% multi-viscosity synthetic & 20% castor. It's the perfect, low-cost, versatile option for your 2- and 4-cycle nitro sport flying applications. It delivers incredible RPM and power gains while maintaining the reliability and consistency you expect from a VP fuel.

You'll see the results and also notice the quality of the fuel container, which is just as important as fuel quality. VP 10% Air is packaged in a pressure-tested, DOT-approved metal container with an inner lining to prevent corrosion. You're guaranteed a high-quality fuel that will perform as well months from now as it does on day one.

[Steve Helmick]

No doubt that team racers, especially interested in fuel economy, have used low oil content in the past.  Perhaps 11%.

Model diesel fuels usea pretty high percentage of kerosene, which has lubricity itself, so they don't need as much oil as a glow engine. F2C guys run as much kerosene as possible, along with the least ether and oil. I've mixed diesel fuel and ran diesels some, but not F2C. I've studied on it, and my friend Tom Knoppi was an avid F2C guy and team member. I met him when I was in HS. By the way, a glow engine runs ok on diesel fuel, but then smells bad. Steve 

[Steve Helmick]

what oil did K&B use in their speed fuel  RAD

It was SAID TO BE "Epoxidized Soybean oil"...or maybe just soybean oil. The GMA "Speed Secrets" article in an AeroModeller Annual (not sure what year...1970, maybe?) said it was 60% nitro. We used UCON oil, but I'm not real certain what type number it was. UCON 625 was supposed to be the stuff most used. We got ours from Dow's Hobby in Seattle...boat racers got George Dow to stock it. 25 gallon drum, maybe? Long time ago! Steve

[Colin McRae]

if we are talking about VP Powermaster fuel this is their list for 10% airplane
An ultra-clean burning fuel containing a 17% castor/synthetic oil

VP AIR fuel is actually 18% total oil, not 17%. At least that is what is stated on the side of the VP container. And the blend is 80% syn/20% castor.

Colin

[Colin McRae]

Why do we use 18%, 22%,28% of oil in our engines? High revving 2-stroke racing dirt bike engines, that spin up at 10k+ RPM, use 3-5% oil mix. With modern AAC and ball bearing engines with tight tolerances, is there a reason to use so much oil?

Has anyone experimented with, say, 5% or 10% oil mixes?

Others have mentioned lubrication and cooling, but there is also piston blow-by. The oil also contributes to the piston/liner seal (sealing efficiency). If the oil is 'too thin' there will be increased piston blow-by and some associated loss of power.

Just follow the specific engine manuf owner's manual recommendations for the amount of total oil in the fuel and you can't go wrong.

Colin

[Brett Buck]

Others have mentioned lubrication and cooling, but there is also piston blow-by. The oil also contributes to the piston/liner seal (sealing efficiency). If the oil is 'too thin' there will be increased piston blow-by and some associated loss of power.

   You absolutely should not be counting on "heavy oil to seal the piston", and most modern engines are hurt far more than helped by more than the bare minimum of oil in the interface. If you get more than the tiniest amount, it varnishes and messes up the clearance. I have seen a bunch of modern AAC engines so heavily varnished up that they wouldn't run right, and in some cases were almost impossible to even start without special measures. One case I recall  was a RO-Jett 76 that the gentleman had run on some typical fuel where he was adding 13 ounces of castor to every gallon - basically Fox Superfuel. It was varnished to the point it could not be started conventionally, and had to be "cleaned" by running regular fuel for a few runs before it could be started "on it's feet" and without priming through the glow plug hold. 

    In some cases it will not run at all, or run with misfires at some place in the flight. If I tried to run GMA or similar in my #2 engine, it misfires heavily in inside corners to the point you can't finish the flight.   It's also much harder to pull through the lines and metering, leading to other run "oddities" in larger engines.


     Thinner oil is easier to shear over a small (ten thousandths of a inch) space and heavy oil will usually significantly reduce the power and/or load the engine to put it in a different running regime - i.e. leaner and flatter. Many times this will also increase the heat, both by the energy dissipated in the shearing of the heavy oil, and by having to run the engine harder. My trick of adjusting the engine by varying the oil content (adding small amounts of thin synthetic oil) depends on this, add 1/4 ounce of KL-198 per tank and it flattens the engine response.

    Some old engines, typically steel liner/iron slug piston engines like the Fox 35, or sintered-piston engines like the Johnson and McCoy have to have heavy castor oil to stay alive and run properly, to fill up the gaps that you need to keep them from seizing. Any current engine made in the past 40ish years are set up to have proper clearances without lots of oil. "Heavy oil to seal the piston" is a function of the ancient past - "traditional stunt values".

    You need just enough oil to keep the parts needing lubrication alive, and to give you some margin if you miss a needle. That does not require lots of heavy oil, it needs just enough. I am no adventurer and haven't tried to find the lower limits, but I *did* run 14% straight synthetic for a season or two with no apparent issues, and have run 17% oil for 25+ years with no lubrication-related failures and minimum varnishing.

    Brett

[Rick's friend Steve]

It was varnished to the point it could not be started conventionally and had to be "cleaned"

Another example is a couple of Ukrainian fliers who flew Stalker 66s and 76s extensively. They used all castor mix, and every dozen flights or so, they had to take the motors and mufflers apart and clean off all the burnt-on crud. When I visited Kyiv for the first time in 2014, I told them I put 200+ flights on my 40VF with an all-synthetic 18% mix without any issues; they were skeptical for the same reasons I heard here. The next year, I saw them switch to a 50/50 mix, 17% oil, and they no longer needed regular "decrudding." I suspect that, if they haven't gone electric, they would have continued moving toward an all-synthetic mix.

I still wonder if modern engines need that much oil(18+%). I'm going to try to run the Stalker 76 model with 15% for a season and see how it goes.

[Brett Buck]

Another example is a couple of Ukrainian fliers who flew Stalker 66s and 76s extensively. They used all castor mix, and every dozen flights or so, they had to take the motors and mufflers apart and clean off all the burnt-on crud. When I visited Kyiv for the first time in 2014, I told them I put 200+ flights on my 40VF with an all-synthetic 18% mix without any issues; they were skeptical for the same reasons I heard here. The next year, I saw them switch to a 50/50 mix, 17% oil, and they no longer needed regular "decrudding." I suspect that, if they haven't gone electric, they would have continued moving toward an all-synthetic mix.

    Same with the Retro, from what I heard. This is nuts, that alone would be reason to use something else.

I still wonder if modern engines need that much oil(18+%). I'm going to try to run the Stalker 76 model with 15% for a season and see how it goes.

    It will probably be fine with that. I ran 14% for several years (without telling anybody to cut down on the predictions of doom) on an ABC engine in the late 90's, it is still fine. But as I said, I am no adventurer, I figure I have about 6 months of serious IC time left and I know Powermaster works.

     Brett

[Dave Harmon]

I ran 14% for several years (without telling anybody to cut down on the predictions of doom) on an ABC engine in the late 90's, it is still fine.

    Brett

Well....I didn't want to mention it either and for the same reason(s)....but I ran 20% nitro, 12% oil in a YS-61 RE Pattern engine at the 89' NATS without any problems. I kept on using it for several years.
I could get the gross weight of the airplane down quite a bit by not carrying around so much fuel.
The gas mileage was great!
The oil content was 10% X2C, 2% Castor.
It ran great.

In a conversation with Clarence Lee from some years ago....he mentioned that K&B X2C oil was actually UCON 1145 that burns at 430 degrees.
This is an older oil that is not mfgd anymore...newer oils have a higher burn temperature...but...I've never had any problems with it even in the RoJetts.
Since then....someone here mentioned that this was incorrect.
I'm not going to doubt Clarence but the other guy was in the know too...I remembered who you are now if you want to chime in.
Back then....a guy could go to K&B and buy X2C out the back door for $8 gal.
Bring your own can or they would sell you a new can with their logo...for $1.

[Reptoid]

In a conversation with Clarence Lee from some years ago....he mentioned that K&B X2C oil was actually UCON 1145 that burns at 430 degrees.
This is an older oil that is not mfgd anymore...newer oils have a higher burn temperature...but...I've never had any problems with it even in the RoJetts.
Since then....someone here mentioned that this was incorrect.
I'm not going to doubt Clarence but the other guy was in the know too...I remembered who you are now if you want to chime in.
Back then....a guy could go to K&B and buy X2C out the back door for $8 gal.
Bring your own can or they would sell you a new can with their logo...for $1.
[/quote]

Might have been me that commented. I was friends with most of the guys that worked at K & B and lived near the factory. They were originally pretty secretive about what X2C was. At that time UCON LB625 and LB 1145 were the most popular oils used by modelers. They are polyalkylene glycol lubricants which still have many industrial uses such as compressor oils. Those "Neat" UCON lubricants had no rust inhibitors and if used straight would develop rust on steel surfaces quickly. Bill Wisneiwski asked Dow/Dupont to formulate a product specifically for Model engine fuel and they did several versions with Bill testing them at K & B. The main difference was/is rust/corrosion inhibitors. The version they settled on was named X2C and was proprietary to K & B. The internal to Dow/Dupont designation was/is MA731. I believe it is still available, but only in large quantities (55 gal. drums)to fuel manufacturers

[Dave Harmon]

In a conversation with Clarence Lee from some years ago....he mentioned that K&B X2C oil was actually UCON 1145 that burns at 430 degrees.
This is an older oil that is not mfgd anymore...newer oils have a higher burn temperature...but...I've never had any problems with it even in the RoJetts.
Since then....someone here mentioned that this was incorrect.
I'm not going to doubt Clarence but the other guy was in the know too...I remembered who you are now if you want to chime in.
Back then....a guy could go to K&B and buy X2C out the back door for $8 gal.
Bring your own can or they would sell you a new can with their logo...for $1.


Might have been me that commented.

Yep...it was you!!
Long time ago....far away!
Thanks for the info...much appreciated.

[Lauri Malila]

Same with the Retro, from what I heard. This is nuts, that alone would be reason to use something else.

    It will probably be fine with that. I ran 14% for several years (without telling anybody to cut down on the predictions of doom) on an ABC engine in the late 90's, it is still fine. But as I said, I am no adventurer, I figure I have about 6 months of serious IC time left and I know Powermaster works.

     Brett

Yep, but unfortunately Retro, especially the earlier 10cc's, did not run well with many synthetics.
They are so tightly fitted at tdc that only castor gave good enough lubrication.
I don't know if that was the only reason, maybe also some of our synthetics burned at lower temperature, and caused detonation. That led many people to endless circle of adding shims, then drilling the venturi, and then adding nitro. All those modifications made the run worse how it was designed to run.
Then we found the Motul Micro oil. It was some sort of castor/synth blend but workee much like castor, just much cleaner. It's not available anymore.
Today, maybe the best option would be 15...16% of Maxima Racing Castor #927.
So, my advise with Retro's is that please test whatever oil but always compare tge results with castor fuel. L

[Peter Klosky]

It's true that kerosene is more viscous than methanol.  But orders of magnitude less than castor oil.

[Dan McEntee]

   I ran SIG Champion 10%N and 20% total oil for many many years. One jug ran the same as the one before it and so did the next one. i would stock up and sometimes use fuel that was at least two to three years old. I'm running a jug just now that I bought back in July of 2020, and runs just like any other I have used. When things went south for SIG and they no long could make fuel, I started to mix my own following recommendations from a thread here on SH to use the VP Products 50/50 nitro/methanol mix as a base, methanol from the same supplier I got the VP-50/50 from, and accumulated castor oil and Klotz Techniplate and Super Techniplate that I would buy over the last several years if i ran across a good deal on it. I mixed the more or less same recipe as the SIG Champion i had still in my stash. Then I would put up back to black flights comparing one to another, measuring and looking for changes in take off RPM, run time on a fixed amount of fuel, and shooting head and exhaust temps with one of those infrared laser thermometers. I never saw any difference in any one them. That's good enough for me  and what and how I fly. As long as I can get the same three ingredients, I think I'll just stick with it. Morgan fuels are OK and I use them in some models on certain occasions, but I don't think it performs the same as the SIG miix. I always seem to have to lean the needle a bit to get comparable power. But I have never experienced any kind of engine damage, "taters" or any really negative symptoms in any  of my engines, ranging from Foxes, Tigers, OS engines of several vintages, and even in Cox engines!!

   Sometimes, if I think to add it, I put in a cap full or what ever is recommended on the label of Randy's "Aero-1" snake oil additive, mainly because I have a supply of it so I figure I should use it. Does anybody know what that is? I also gave a couple of cans of the SIG "Lubricin N-1" oil that I have a can  or to of. Does anyone know what that is? I can't really tell any difference by adding either, but I don' tthink it's hurting anything either.
   Type at you later,
    Dan McEntee

[Dave Harmon]

I also gave a couple of cans of the SIG "Lubricin N-1" oil that I have a can  or to of. Does anyone know what that is?
    Dan McEntee

Clarence Lee spoke of Lubricin N-1 in his engine column in RCM back in the mid 60's when there was some discussion about fuel mixing.
As I remember....N-1 was/is a 'slickener' intended for speed flyers who were looking for maximum RPM at any cost.
About 1/2oz per gallon or so was all that was used to notice an improvement.
For our use in C/L Stunt engines....the 'snake oil' moniker is likely appropriate....    

[Motorman]

I still have a pint of Lubricin I got from RedMax. I was adding 2% to my big Goodyear fuel. Never saw where it did anything special.

I also have a small yellow bottle of Molly Slip. 1/4% is all you want because it really cokes up your engine.

We always ran 10% castor in our racing diesels. We tried 5% once and performance went up but, the engine was destroyed at the end of the day.

MM  

[Dave Hull]

I think that the F2C guys were adding a tiny bit of lubricin to their fuel. If I remember correctly, the purpose was that it made the carbon on the piston much easier to remove during cleaning. I never had any, so I never tried it. Maybe Tommy would know.

If you guys really want to discuss oils again, you should review Keith Trostle's summary of the Kilsdonk oil testing. That summary then gives the grounding to study John's article in detail, if still interested. It discussed the actual performance testing on model engines of the different available oils and fuel mixes with very low oil content.

[Reptoid]

  Lubricin N-1.

     I have posted the characteristics on here before but couldn't find the link. N-1 is a derivative of the castor bean refining process. It's sole purpose in fuel is to retard the molecular elongation process of castor under extreme heat. In simpler terms, it delays the thickening and congealing of castor at high temps thus acting as a detergent avoiding some of the gum and carbon when running high percentages of castor. It is useful in percentages of 1-2%. If you add more than that you run the risk of cancelling the main benefit of using castor; protection from lean, overheating runs. The use of N-1 has almost disappeared now that synthetics are used in much greater percentages for general modeling use. Lubricin does Nothing if added to an all synthetic fuel. It is NOT a good lubricant by itself. Keep in mind; castor and N-1 are both vegetable derived lubricants and can go "bad" from careless storage. Rancid or contaminated castor or Lubricin can cause white flakes in the oil or fuel mix. Lubricin and castor that are pure will not cause it.

[Chris Wilson]

Why do we use 18%, 22%,28% of oil in our engines? High revving 2-stroke racing dirt bike engines, that spin up at 10k+ RPM, use 3-5% oil mix. With modern AAC and ball bearing engines with tight tolerances, is there a reason to use so much oil?

Has anyone experimented with, say, 5% or 10% oil mixes?

Low oil content is well tolerated with diesel or HCCI engines because of the increased lubricity of kerosene but with methanol which is much drier, a higher oil content is needed.
  In regards to comparing a larger engine to a smaller one in regards to oil percentage it is the ratio of volume to surface area that is critical. The smaller the engine capacity the larger the surface area as compared to the volume, and here a larger surface area can be regarded as potential loss of compression and gas flow. So raising oil percentages compensates for a diminishing volume.
  In regards to heat rejection comparing a high revving 2 stroke racing dirt bike that is water cooled to a miniature air cooled one really is about the liquid distributing localized heat far better than any air cooled engine can, hence the need to supplement heat distribution and rejection through total loss lubrication.

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