Fuel

[Roby]

Hi guys, I've got an os 46ax and an os 81 alpha and I've been given Duraglo 10%, Duraglo 5% and Dynaglo 10% from model technics. The engines manual says that I better use 18% synthetic oil but those fuels contain 15%, are my engines going to be ok if I use them? Thanks

[Ross Clarkson]

Absolutely, no problems at all. Simple explanation but i am sure someone will give you a longer reason why they will be ok!

[Bruce Richards]

Posting below from Steve Hargreaves which I deleted by acident. Sorry

 

Well.....fuel is a controversial subject...ask 10 modellers & you'll probably get 11 different answers. Model Technics are a long established & well respected company supplying model fuel to the aeromodelling public so I'm sure they know what they are doing......

 

HOWEVER....

 

I personally wouldn't use either fuel, particularly if the motors are new. Both fuels would invalidate the warranty as they don't contain enough oil.....!! Dynaglow is 2% castor & 8% synthetic.... & Duraglo is 6% castor & 9% synthetic. Duraglo would probably be OK in your four stoke but a bit low on oil for a two stoke motor..... Just Engines offer some good advise on fuel here.

 

Personally I use the Southern Modelcraft Mo glow fuel in both 2 & 4 stroke motors.....2% castor & 15% synthetic....cheap as chips (£12 s gallon) too!! Only problem is you can only get it at the shows (so stock up when you go!!!)

[Steve Hargreaves - Moderator]

Aaarrgghhh!! I can usually delete my own posts without any help from you Bruce.......

[Roby]

Thanks guys for the advises, the problem is I went with my engines manuals to the shop and although it says to use a minimum of 18% oil, those are the fuel I've been given, and the expert behind the counter said that they are perfect fuels for my engines. I don't wanna have problems with my engines, should I just mix some more oil?

[Steve Hargreaves - Moderator]

First question...are the engines new?

 

If yes & you have a problem with one then Ripmax/OS probably won't honour the warranty as you have used a fuel with less than the recommended amount of oil. An interesting/mischievous thing to do is to ask the guy behind the counter if he would stand by his advise & honour the warranty if you have a problem  !!!!  I suspect his answer will be short & end in "off"

 

If the motors are not new then its pretty much up to you.....IMHO the Duraglo would be a better bet than the Dynaglo & as I said in my post Model Technics have been making fuel for years & years & are a very respected company....if they think this ratio of oil is OK then who are we to argue...they know a darn sight more about it than I do after all...

 

If this is the only fuel you can get then go for the Duraglo. 5 or 10% nitro probably doesn't really matter but I'd go for the 10%....the higher nitro allows a slightly richer mix (because it releases oxygen into the combustion chamber meaning you can burn more methanol) & a richer mix means more oil going through the engine......make sure the motor is not tuned too lean; if necessary, get help from the guy at the patch who never fiddles with his engine. Correctly set engines don't need constant fiddling & most engine problems are caused by the users..... ie us lot!!!

 

Then...when you visit one of the shows next summer grab a few gallons on the Southern Modelcraft Mo-Glo stuff & relax in the knowledge that you've saved a wedgeful of cash & got an excellent fuel mix as well.....!!!!

[kc]

At least one model shop stocks Southern Modelcraft fuel.  Modellers World in Hornchurch stocks this brand. 

Edited By kc on 15/12/2010 11:43:30

[Roby]

And what about adding up some EDL oil and make it to an 18% oil mix? Is it going to work well?

[Myron Beaumont]

Phew

Never used synthetic & never had a single engine wear out or get gummed up using Duraglo 5 % in 2 & 4 strokes !!! What's it all about ?

[Steve Hargreaves - Moderator]

You could do Roby but I don't think I'd bother....as I say MT are a well respected brand & don't sell inferior fuel. Just don't run your motor too lean & you'll be fine I'm sure....

 

However Ripmax/OS won't cover your warranty if you have a problem as it has less oil than recommended.....

 

Myron.... Duraglo has 9% synthetic oil in it so if you use Duraglo then you have used synthetic oil....

 

Personally I think synthetic oil is far superior to Castor....after all it has been designed in a laboratory to meet the requirements of the bearings etc used in our engines. It will never vary in quality or constituents. it burns cleaner & doesn't turn your engine light brown. Castor Oil comes from squeezing the seeds of the castor plant...it is a natural product & its qualities will therefore vary.

 

Incidentally Castor Oil dates back to around 4000BC & was used by the Ancient Egyptians....its well known that Tutenkahmun used to get through several engines during a pylon race meeting.....if only he'd had modern synthetic oils then I'm sure he would have siezed fewer motors......

[i12fly]

May be a silly question but how would OS/Ripmax know if you'd used Duraglo or Southern Modelcraft? If you run it lean you'll damage your engine in a similar way whatever, and presumably they would say go away?  Incidentally I've used both at 10% and have had no problems. I feel I get a bit more power from SM but I've not done back to back tests on the same day.

[Steve Hargreaves - Moderator]

You're absolutely right i12....how would they know....unless you told them of course. It got me wondering actually...I wonder how many people have had a warranty claim on an engine rejected because they'd either used insufficient oil or had run the motor lean....

 

I also got to thinking about this whole subject of oil content & I think most engine manufacturers state a percentage of oil which must be used in their motors but not the type of oil. So if we used 18% rancid chip oil would that be OK whereas 15% synthetic purpose made oil wouldn't be....H'mmm!!!

 

Actually if you look at many fuels 18% oil isn't that easy to find....Optifuel is 15%...Coolpower...15%...Aerojuice...15%

 

So whats a guy supposed to do? & Who do we think knows most about it...the engine manufacturers or the fuel manufacturers??

 

Interesting world isn't it....?

[Roby]

It is, that's why I was hoping to get some help from you guys, I'm new at this hobby! Thanks

[Peter Beeney]

   Having just read this thread, can I confirm, at least for myself, what seems to be at least one fuel/oil ratio. I’ve mentioned this before, in another thread, that from the time that Southern Modelcraft first started mixing fuel I’ve always adopted the same procedure. I just buy eight gallons of straight synthetic fuel, plus a gallon of pure methanol. I then top up each gallon with one pint of the methanol. From reading Steve’s post, concerning the other fuels that contain only fifteen percent oil, as against the more usual seventeen percent, then perhaps I’m not far out.
   As Bruce said, the SM fuel is a 15% synthetic, 2% castor mix, a total of 17% oil by volume. Adding a pint of methanol/gallon thins this down to around 15% oil by volume. It also makes the total of nine gallons a tichy bit cheaper overall; I have noticed that some exotic brews seem to be quite expensive.

   I use this for everything, including running in my own and other people’s engines. When running in, to add some extra piece of mind, and lubricant, you can buy a bottle of castor oil from Boots and add a large globule of that to the first half gallon. I used to do that, years ago, and then one day when running one of the first OS 40 four-strokes I placed a jam jar under the crankcase drain tube. After the motor had run for a while, we could not believe the amount of oil that was pumped out of the crankcase. I was just observing this because the owner, who was not really familiar with engines, was a bit concerned that the big end etc. might not be getting enough oil. This, of course, was even then only part of it, I suspect that the majority amount of oil in the fuel was being blown out of the exhaust anyway! After that, I’ve never had any qualms about how much oil the engine receives when running in; I consider it’s adequate. That’s not to say that my opinion could be considered a recommendation, though.

   Four-stokes, especially Saito, seem to benefit from the addition of a dollop of nitro, around 10%; and the general impression that I’ve always seemed to get is that four-stokes run on a lower percentage oil mix anyway. One extra pint in a gallon container pretty well fills it up, if I had some bigger containers I have toyed with the idea of adding even more methanol. One more pint takes us down to around 13% oil, but still more than the 10% of Dynaglo, and I think that provided that I’m aware of this, when twiddling the mixture needle for instance, then that shouldn’t be a problem.
   Later on, when the weather improves, I could try a little experiment, by dividing my one of my oddball 9 pint gallons equally into two separate cans and then adding half a pint of methanol to each. Then noting what we get on the tacho, as a comparison.

   As Steve remarked, I’m sure Model Technics, and likewise Southern Modelcraft, are both very reputable long established businesses. If they were not, then it’s most likely they would soon disappear. Their fuel must consistently be top quality, so it’s unlikely that there would be any problems.

   I’ve been running this for perhaps around thirty years, so I guess the initial test period is satisfactory, at least. Now for a lengthy trial of the fuel in a further multifariousness of engines, airframes, and variety of weather conditions………….

   And I also couldn’t agree more, this is the 11th answer from the 10th modeller……….

   PB   

                           

[Steve Hargreaves - Moderator]

Blimey Peter...sounds like a lot of work......maybe just use the standard stuff & use the time saved to test some batteries!!!!

[Peter Beeney]

   That’s most unlikely, Steve, I don’t believe in work much, as I’ve said a few times before, I spent my working life practising doing as little as possible, and I’m now not going to change the habit of a lifetime!

   Actually, I get through a reasonable amount of fuel, and the savings (from SM) really are worth it. Although, to be completely fair, perhaps not entirely just from the fact of buying a gallon of methanol. It takes longer to write it than to do it, after all, it’s only filling a pint jug and pouring into a container, a couple of minutes at most, and I’m very much more than satisfied with the resultant performance. I’ve always thought that there is more than an adequate sufficiency of oil in the standard fuel; methanol is the fuel, oil is the lubricant, and I’m not sure that it adds to the combustion qualities of the fuel; obviously you can buy fuel with a lower oil content, but at what price? As an OAP if I can make savings it all helps. In the best aeromodelling traditions, my wallet has very little visible means of extracting the contents.

   Now I might just try leaning it out a bit more…..

   May battery testing station is fully automatic, I simply plug the battery(s) in at night and read the results in the morning! It’s that lifelong habit that keeps me going, you see! It’s in the back of my car, so when I’m testing someone’s pack and we are enjoying a fix of flying, plus a doze in the sun, that’s even better! So I can’t admit to any excessive over-time working practises there, either….. …Even if I could, I don’t think anyone would pay me…..

   Talking of batteries, tests, and saving money, I’ve found a pack, 4 Ni-MH AA cells for less than £2. Not the greatest in terms of capacity, but the first view is eminently satisfactory and certainly more than good enough to justify me making an effort and quickly soldering them into a rx pack for some practical flying lessons in the trainer. When the weather improves I can see that model getting plenty of exercise at least; so I shall also be able do some surreptitious tests on their ability to continue to supply the power at the same time; and I think they will be up for it, unlike some others I’ve seen.

   I’m also still square-bashing some other makes of batteries, too, but this is perhaps not the time nor thread to discuss this. Later on, if can stay awake for long enough, perhaps I might be tempted into a little report, but it might not be that interesting.

   Right, now I’m off to neuter the alarm clock……..

   PB     

                                      

[Former Member]

[This posting has been removed]

[Peter Beeney]

   Yes indeed, I think I can learn something new everyday. As I noted in my first post, the first thirty years of testing seemed to have been reasonably satisfactory, maybe it’s now time to try a new trick or two!

   Oddly enough, I’ve always found it quite difficult to judge the rpm’s of an engine just by listening to it. This is both full and model size contraptions, I’ve always had to use a tachometer of some sort. Although I have found my hearing is quite perceptible to the rate of change in revolutions if the throttle opens or closes; albeit if it’s only a few revs, it’s still easily noticed.
   Also knowing the speed of the engine tells me a little bit more about how the model is expected to fly. For instance, if the 12 by 6 ACP on my Irvine 53 was spinning at 10,400 rpm, as it was yesterday, then I know the plane will fly at around 60 mph. That’s a flexible figure, though, knock off 20% for a bit of prop slip, then shove it back on again for unloading in the air! Then it’s a bit of a high wing drag though, so maybe that’s another 10% reduction.

   With regard to the oil content, purely for interest, lets bandy a few figures around. Lumping all these engines together and calling them two-strokes for a moment, that’s motorcycles, chainsaws, lawn mowers, even petrol model engines. These petrol fuelled movers seem to run on generally on a 25 : 1, up to as high as a 60 : 1 petrol/oil mixture. That’s around 4% oil down to around 1.6% oil. My 15% methanol/oil mix is a 6.6 : 1 ratio. So it would appear that this mixture/ratio is still quite relatively high. Of course there are differences, many petrol two-strokes have ball or roller bearings, for a start. But there is still the piston/cylinder plain surface, also the gudgeon-pin/piston plain bearing, etc. to lubricate. Nevertheless, as I said, I’m satisfied that there is sufficient oil in the fuel.

   As I remember, a small question with two-stoke motor cycles was that of possible lack of oil when the throttle was closed, such as on long down hill runs. However, I guess this doesn’t apply much to model aircraft. Also, but the memory really is extremely vague now, for racing motorcycles, where the oil was injected straight into the inlet manifold, it was calibrated such a way that the longer and wider open the throttle was held, the more oil was injected. But I’m not sure that racing two-strokes were that successful anyway.

   Looking around at the strip, it seems that every fuel container is a different brand. But they all seem to perform quite happily. So is it a case of just simply a little of what takes your fancy does you good? Over the years I don’t think I’ve seen anyone with problems that can be directly attributed to the fuel. I’ve had to change some bearings, in a couple of same-make/type engines, but then subsequently found out the manufacturer had a problem anyway.

   So, now might be an opportune moment to simply say ‘Cheers, here’s to the next thirty years!’

   PB  

               

[Former Member]

[This posting has been removed]

[Steve Hargreaves - Moderator]

The main reason for such low oil content in a petrol motor is that petrol itself has some lubricating properties where as methanol has er none!!! Petrol is derived from oil after all.....its simply a "lighter" fraction of crude than oil.....

 

Not sure that Mick Doohan would agree that racing two strokes weren't that successful....the 500cc 4 cylinder Grand Prix bikes were some of the fastest accelerating wheeled vehicles on the planet........!!

 

The problem of lubricating 2 stroke bike engines on long down hill sections is only really applicable to petroil lubrication....a closed throttle equals no (or very little) fuel....equals no oil. On the pump/injection lubricated motors by Honda/Yamaha etc the pump ran at engine speed & the pump stroke (& hence volume of oil supplied) increased as the throttle opened.....hence high speed & wide open throttle equalled maximum oil supply.....

[Chris Channon]

Hi all, anyone know where i can get Model Technics fuel delivered , no-one round here seems to stock it?

Thank you

Chris.

[Former Member]

[This posting has been removed]