Interesting note on fuel for Testors engines.

batjac Thu May 18, 2023 2:16 am

One of the things I'm doing in prep for S.M.A.L.L. is getting my Ambush plane ready by installing a Testors 8000 engine in it. It has been Black Widow powered since I built it, but I figured that it really deserves an 8000 engine, as that is the engine it was designed for.

So, I dug up the instructions for a Testors 8000 and read them. Hmmmm.... According to the Testors instructions, Testors engines should be flown with 100% synthetic oil. Testors = castor bad. I never knew this! According to the instructions, Testors fuels weren't made with castor! Now I'll have to mix up a quart of Testors specific fuel for my Testors engines, and flush the ones I have run with castor based fuels per the instructions. The instructions recommend 15% nitro fuel, but the engines are rated for up to 40%. No mention of total oil content, so I'll just go with 20% oil and 25% nitro.

The Discoverer Mark

Levent Suberk Thu May 18, 2023 2:55 am

http://sceptreflight.com/Model%20Engine%20Tests/Testors%208000.html

Interesting note on fuel for Testors engines. Screen89

GallopingGhostler Thu May 18, 2023 6:25 am

Thanks Mark and Levent, for pointing out the fuel requirements. Then the standard 15+% nitro R/C fuel with 16% synth and 2% Castor would probably be at home with the 8000. Seems that with such low Castor, would less likely gum up the starter. I found it interesting that to ensure the engine could run on all synth fuel, Bill Netzeband prepped the engine with special bronze crankshaft bearings and a different piston socket arrangement. This is not possible with our Coxes due to the piston ball and socket joint and lack of bronze bushings for the crankshaft.

I also found it interesting that our standard Cox 15% nitro with 10% synth and 10% Castor would be good with the Sanye factory's AP .09 engines, due to the non-bushed aluminum connecting rod. I think I read in the Sanye AP .15 based on the .09 (.136 cu. in. displacement) also recommended a Castor based fuel, and don't skimp on the oil. Also of interest, Cox oil package is good for the K&B Sporster series engines. Seems many a modeler ruined the engines by using fuels with less than 20% oil with less than half of that oil as Castor, then blamed the manufacturer for failing to fuel it properly.

rsv1cox Thu May 18, 2023 8:12 am

I have several of these engines and can attest that castor oil will lock them and the rotomatic starter up, so not everybody reads instructions or used Testors fuel. But, Berrymans is the cure for both engine and starter quickly returning both to operational status. But, Berrymans and other heroic measures did not clean the castor goo from the throttle sleeve of my Cox Ryan ST which needed complete disassembly before that goo could be removed. Same for the throttled Wen-Macs.

Checked my lone can of Testors fuel (empty) to see if they mentioned lube. Don't. But it is registered with the New York Fire Department......or equivalent

Interesting note on fuel for Testors engines. P1015432

Interesting note on fuel for Testors engines. P1015433

Ken Cook Thu May 18, 2023 4:34 pm

I ran a entire gallon of Cool Power 30% nitro heli fuel which is 24% full synthetic oil through a Cox .049 product engine. I ran it with 3" props, I ran it with 8" props as lean as I could run it. I was driving my club members crazy doing it. I would get to the field and just let it run in the corner. As soon as it would run out of fuel, I would fire it up again. No ball socket failure, no wear that was even noticeable in the ball socket. I reset them with little to no play. From feel , it was no different than when I started. I disagree that synthetic fuel will wipe out a Cox engine because I tried to do it. The only fuel I ever had that wiped out a Cox Black Widow was Aero Dyne 70% nitro fuel, the rod came out the side of the case. I have no idea or remember what oil was used in that fuel. But, I disagree that synthetic fuel will ruin a Cox engine. I use Klotz Super Techniplate in brand new 1940's engines and nothing wears out or breaks.

GallopingGhostler Thu May 18, 2023 10:43 pm

Ken, overall, I gather that the impetus for use of Castor oil had to do with protection during a lean run. Seems most of our engines entered ruin when a lean run was entered, reducing the available lubrication in the air fuel mix, overheating an engine and vaporizing and combusting the synthetic with no oil left to lubricate metal surfaces.

Departing with a sense of humor, Wink

the dangers of using synthetic oils has been thoroughly documented even as far back as use by the Spagthorpe Motorcycle Company, famed inventor of the radioactive powered motorcycle car. Paranoid

https://cybermotorcycle.com/archives/spagthorpe/synthetic.html Don't let me keep silent to let you know that you all have been forewarned! Very Happy

Spagthorpe Maintenance Bulletins wrote:Beware of synthetic oil! It can do terrible things to you and your beloved motorcycle. It will not only leak out of your engine faster than you can put it in, but it will also cause your oil filter to clog and implode, dumping debris and dirt into your lubrication system. It also will make every part of your bike permanently slippery because of its linear molecular chain dispersion action. Then it will leak onto your kickstand causing it to retract automatically, dropping your bike on the ground! But that's not all...

Synthetic oil will round off your gears and spin your bearings. It will also splatter onto your seat causing your girlfriend to fall off in the apex of a turn and she'll never ride with you again. Synthetic oil coats your sight window and your timing window with a whitish pro-emulsification additive that is both non-removable and highly corrosive. Synthetic oil will completely leak onto the ground overnight and your dog will drink it and die.

Synthetic oil will wear out your tires and make your battery leak. It will give you the desperate need to urinate after you put your full leathers on and then jam your zippers shut. It will contaminate your gasoline causing your bike to stall on railroad tracks and accelerate uncontrollably near police cars. It will make it rain during rallies and on weekends. It will lubricate four timing belts causing them to jump teeth and break your valves to bits. Synthetic oil chemically weakens desmodromic valves and causes the clearances to change every six miles. Then it melts the black soles of your riding boots night before you walk across your new carpeting.

While riding past groups of attractive women it will cause both of your handlebar grips to slip off at the same time so you smash your windscreen with the bridge of your nose. It also causes your swingarm to crack, your studs to break, and your rotors to warp, and then it voids your warranty by changing your odometer reading to 55,555. It also dries out your wetclutch and wets your dryclutch. It makes your clutch slave cylinder seal fail in the heaviest traffic on the hottest day of the year while putting an angry wasp in your helmet for good measure.

Synthetic oil hides your 13mm socket and puts superglue on your earplugs. Synthetic oil will scratch your faceshield and make your gloves shrink two sizes night before trackday. Synthetic oil stole your neutral and sold it to the Chinese for £1.25. Synthetic oil will make you grow a tail. Synthetic oil will write long crazy e-mails to your Internet friends and then sign your name at the bottom!

**944_Jim** Fri May 19, 2023 7:36 am

I have nothing of significance on this one. But I DO remember that Testor's fuel had a different smell in the can and while running. I also seem to remember it was pink.

While these are vague memories, I also seem to remember my Cox engines ran differently on Testor's fuel, and I didn't appreciate how they ran on it. I can't remember why I preferred to run Cox fuel in my Cox engines beyond I couldn't afford the higher nitro blend.

I also remember Testor's engines seemed to run a bit flat on the lower nitro-content Cox fuel I used (economizing in my childhood). I can only believe the available Testor's fuel had more nitro than the Cox fuel. But this is only supposition decades after the events took place.

Cox International Tue Aug 15, 2023 11:57 am

Interesting!

There have been other tests made where castor oil was gradually reduced to about 20% or so; at which point the engine failed.

We also had a customer not too long ago that purchased three engines from us on the same order. He phoned a few weeks later to let us know that all three of the engines had seized up. Turns out he used 25% nitro with 100% synthetic oil.

Perhaps a factor is cylinder piston fit and whether the setup is SPI or not?

Ken Cook wrote: I ran a entire gallon of Cool Power 30% nitro heli fuel which is 24% full synthetic oil through a Cox .049 product engine. I ran it with 3" props, I ran it with 8" props as lean as I could run it. I was driving my club members crazy doing it. I would get to the field and just let it run in the corner. As soon as it would run out of fuel, I would fire it up again. No ball socket failure, no wear that was even noticeable in the ball socket. I reset them with little to no play. From feel , it was no different than when I started. I disagree that synthetic fuel will wipe out a Cox engine because I tried to do it. The only fuel I ever had that wiped out a Cox Black Widow was Aero Dyne 70% nitro fuel, the rod came out the side of the case. I have no idea or remember what oil was used in that fuel. But, I disagree that synthetic fuel will ruin a Cox engine. I use Klotz Super Techniplate in brand new 1940's engines and nothing wears out or breaks.

balogh Tue Aug 15, 2023 1:27 pm

I know the castor or synth is a controversial discussion among COX engine owners, and I am the advocate of all- castor lubrication up to at least 20% in my home blended fuels.
It leaves sticky oil on your plane after every flight, tends to thicken in engines left dormant for months, and more importantly, clogs the 3 delicate orifices on the - mainly 010 and 020 smaller size- TeeDees if not blown free after the flight season ends. But for the longevity of my COX engines it is worth living with the consequences of using castor, in my opinion. (Importing engines or parts from outside the EU is a nightmare, I just had to pay twice the 27% Value Added Tax after a COX Killer Bee imported from the UK and now claim at least one of the 2 VAT-s from ebay with tons of proof of VAT having been paid twice that I have to present)

For this latter castor inconvenience i.e clogging venturi orifices, I use compressed air spray cans they sell as dust remover from office appliances like keybords. After the daily flight session I crank the rotary valve closed on the TeeDee shaft and press the tube extension of the spray button into the tapered venturi then release pressurized air from the can. All orifices on the venturi will be air-flushed clean without the need to disassemble the carb, and restarting the engine weeks later is easy with the orifices clog-free.

GallopingGhostler Tue Aug 15, 2023 9:14 pm

Cox International wrote:We also had a customer not too long ago that purchased three engines from us on the same order. He phoned a few weeks later to let us know that all three of the engines had seized up. Turns out he used 25% nitro with 100% synthetic oil. Perhaps a factor is cylinder piston fit and whether the setup is SPI or not?

There are several questions that come to my mind, and that is his environmental setup that was used for running the engines. Were the engines fully cowled? Was the user employing oversized props working the engine hotter and harder? With the Coxes, I have always run them with a minimum cowling of extended fuselage sides, but head area clearly stuck out in the breeze when flying.

Never had any problems with overheating. Also, never set them up to run lean, always tweaking a touch rich so when the prop unloads in the air, the engine leans out to peak power.

There was a rather detailed study done by an individual about 15 years ago, documentation no longer available, who was altering the Castor oil levels. His conclusion was 6% was sufficient to maintain absolute minimum adequate protection. It supported the defacto standard (which IMO then includes a safety factor), the current 20% oil with half (10%) as Castor oil recommendation.

I won't doubt that in certain situations, one can possibly use a modern all synthetic. (I recall the Bell UH-1H Huey's Lycoming T53-L-13 1,500 BHP I believe - gray matter is fading Laughing

turboshaft engine used a special rather expensive red colored synthetic turbine oil to lubricate and cool its internal bearing surfaces, but really don't know much beyond that as to whether suitable for other use.) However, my impression is with caveat. Never afford a lean run. The reduction in overall oil content by a lean run can be devastating IMO. Also, never run hot by overpropping and creating more heat by working the engine harder without adequate Castor oil protection.

Since I tend toward larger diameter and steeper pitched props, I made sure I run with at least 10% Castor with overall oil of 20% or more. (The reed valve engines have excellent torque characteristics.) This is in light of the hottest portion of metal, the ball and socket joint of the Coxes needing greatest protection, along with the un-bronze bushed bare aluminum crankcase bearing surface supporting the steel crankshaft.

Since it doesn't take much to have a lean run, the appropriate Castor oil content helps guarantee a longer life engine, IMO.

HalfaDave Wed Aug 16, 2023 6:46 am

Hi All,
I like the smell of Castor Oil, passed thru a model airplane exhaust. Smile

Just pick a pit that is downwind of the electric planes !
Got that t-shirt !
Take care,
Have fun,
Dave

andrew Wed Aug 16, 2023 8:22 am

There was a thread in RCG back in 2010 by a poster who had done extensive testing regarding oil content and lubrication packages that combined castor and synthetic oil. His results contradicted conventional wisdom then and, pretty much, today's expectation of needed castor oil usage. As you can well imagine, the post was like throwing a rock at a hornet's nest and raised the ire of many readers. However, rather than relying on the "Well, Uncle Bob said ........" approach, he had documented his testing and was quite thorough in his methodology. Essentially, he was able to run as little as 16% total oil with only 8% castor in the package. Rather than post his findings, which are a little long, I've attached a link to the RCG thread. His results support Ken's experience -- the need for castor oil in these small engines is overrated and, when combined with synthetics, overall performance is improved.

YMMV!

http://www.rcgroups.com/forums/showthread.php?t=1325147

balogh Wed Aug 16, 2023 9:22 am

Very interesting experiment in that article...even though I have never had a COX engine with as short as less than 10 hours trouble free runtime, though I have at least 20% castor and minimum 20% nitro in my blends, that ensure proper temperature for castor polymerization . I have a TeeDee 051 with hundreds of hours runtime on it, and COX once also exposed an engine to continuous run experiment, where even after 400 hours the engine still worked, but needed electric starter.

Levent Suberk Wed Aug 16, 2023 10:02 am

Cox International wrote:
Interesting!

There have been other tests made where castor oil was gradually reduced to about 20% or so; at which point the engine failed.

We also had a customer not too long ago that purchased three engines from us on the same order. He phoned a few weeks later to let us know that all three of the engines had seized up. Turns out he used 25% nitro with 100% synthetic oil.

Perhaps a factor is cylinder piston fit and whether the setup is SPI or not

If pistons are made from aluminum then they could be seized, because aluminum's thermal expansion coefficient is roughly three times higher than steel cylinder. This results in greater volumetric expansion of the metal upon heat.

GallopingGhostler Wed Aug 16, 2023 10:50 am

HalfaDave wrote:I like the smell of Castor Oil, passed thru a model airplane exhaust.

I like Dave's attitude, reminds me of, "I love the smell of burnt Castor oil in the morning, it is the smell of victory!" Very Happy

(Adaption of a quote from 1987 movie, Good Morning, Vietnam!)

balogh Wed Aug 16, 2023 11:50 am

Levent Suberk wrote:...

If pistons are made from aluminum then they could be seized, because aluminum's thermal expansion coefficient is roughly three times higher than steel cylinder. This results in greater volumetric expansion of the metal upon heat.

Very well said Levent, honestly, I simply do not understand the concept of aluminum COX pistons which are doomed to either seizing when hot, or, if loose fit enough to prevent hot seizure, hindering engine start with low compression when cold. Aluminum pistons in steel cylinders can only work in my opinion, if fit loose for the difference in thermal expansion, but fitted with rings all the same, to produce compression even when cold.

Cox International Wed Aug 16, 2023 12:43 pm

Just to clarify this sentence "There have been other tests made where castor oil was gradually reduced to about 20% or so; at which point the engine failed."

What I meant to say was 20% of the oil content being castor; hence about 4% castor, 16% synthetic is where engine failure happened, according to extensive testing.

We recommend that at least 50% of the oil content being castor. I mean, we love selling spare parts Very Happy

but, in good conscience, cannot encourage our customers to test limits that may damage their engine. Imagine the outcry if we did and they had to replace parts...

Levent Suberk Wed Aug 16, 2023 2:26 pm

Ken Cook wrote: I ran a entire gallon of Cool Power 30% nitro heli fuel which is 24% full synthetic oil through a Cox .049 product engine. I ran it with 3" props, I ran it with 8" props as lean as I could run it. I was driving my club members crazy doing it. I would get to the field and just let it run in the corner. As soon as it would run out of fuel, I would fire it up again. No ball socket failure, no wear that was even noticeable in the ball socket. I reset them with little to no play. From feel , it was no different than when I started. I disagree that synthetic fuel will wipe out a Cox engine because I tried to do it. The only fuel I ever had that wiped out a Cox Black Widow was Aero Dyne 70% nitro fuel, the rod came out the side of the case. I have no idea or remember what oil was used in that fuel. But, I disagree that synthetic fuel will ruin a Cox engine. I use Klotz Super Techniplate in brand new 1940's engines and nothing wears out or breaks.

Hi Ken, I read that Klotz Super Techniplate page:

LUBRICANT TYPE: 80% Full Synthetic, 20% BeNol Castor Oil

https://klotzlube.com/shop/ols/products/super-techniplate

Interesting note on fuel for Testors engines. Scree151

Levent Suberk Wed Aug 16, 2023 2:32 pm

If you use Klotz Super Techniplate oil, then total oil consists of 16 percent synthetic and 4 percent castor oil, if 20% oil used in fuel.

**Admin** Wed Aug 16, 2023 2:33 pm

Cox International wrote:I mean, we love selling spare parts but, in good conscience, cannot encourage our customers to test limits that may damage their engine. Imagine the outcry if we did and they had to replace parts...

What you need to do is figure out a precise oil mixture to recommend where the engine grenades shortly after the warranty period is up.

lol!

That's what all the big companies are doing these days. Like with my Samsung Smart TV, losing a strip of backlights about 2 weeks after the warranty expired.

Ken Cook Wed Aug 16, 2023 3:44 pm

I use 3 different Klotz oils. One is Techniplate 100% synthetic while the other is Super Techniplate20% castor as you mention. The third is the Benol which is all castor. Cox engines are inexpensive and widely abundant. I was more concerned with the ball socket myth and how it would disintegrate. Well, it didn't and I'm currently running the engine on a free flight plane.

The Morgan Heli fuel I was using is 100% synthetic and 24% total oil content.I've run this many times on iron piston engines. I also use Powermaster Ro-Jett blend 100% synthetic 22% which is no longer available. I have several gallons on hand and I use that quite a bit exclusively on Cox engines.

I don't know what people are doing when I hear that for instance 3 engines were ruined using synthetic fuel. I find it incredibly hard to believe actually. I would further like to know what oil brands were being used. For this reasoning is why I set out to see for myself if indeed it would happen. I read about this hundreds and hundreds of times.

I've used synthetic successfully and I plan to keep doing it. What I've used above has worked for me. Most will still argue that it will ruin a engine but I haven't found conclusive evidence on my end to support that. I feel as long as the oil content is correct in volume, your good to go.

GallopingGhostler Wed Aug 16, 2023 11:11 pm

Ken, I think we may have a better answer if we know what was the environment (exacting specifics on fuel, engine cooling - type of cowling, glow head element used, tank and plumbing, props used, type of starting if electric, needle settings, venturi set-up and clearance, cleanliness, strictly bench run or in flight use, etc.) those engines that wore out prematurely were operated in.

I recall sometime back, someone was using in either RCG or RCU forums, an Enya .09-IV TV with a way oversized prop, not 7 or 8 inch and respectively pitched within its power band.

He really needed to use a larger displacement engine or make do with the weaker power on right sized props. Others pointed out to him, but he continued stubbornly with his own logic. (I guess having recently graduated with a scientific degree meant he knew automatically more than others.)

Haven't heard much since, I guess that is just life. Tired w/ Coffee Read

But, I do concur with Bernie's recommendations overall for success engine runs using generally accepted props (diameters and pitches). Those not willing to experiment and wanting to ensure maximum, trouble free engine life stick to manufacturer's recommended fuel formulas.

Those on the competitive cutting edge in order to afford the winning edge over others and experimenters have a lot of freedom to their choices, with or without consequences.

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Interesting note on fuel for Testors engines.

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