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[Rusty]

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[Eric Viglione]

If I had to wager a bet, I would guess the main difference, at least the one that is giving you fits, is fuel viscosity due to oil content and type.

The Sig is a lot thicker and is why you are opening your needles and nothing runs the same.

Over time, you may note other issues with Sig, like plug life and bad low idle with the R/C engines due to plug taters forming, but the immediate problems you noted are too soon for those problems just yet.

Use it up and find something you like better. Hopefully you have other options locally. You could also cut your Sig by mixing it with some Synthetic fuel of the same nitro content, which would cut the oil a bit until you use it all up. Not a solution for the oldies engines, but ok for your others.
Eric

On paper they should be the same: nitro 25%, oil content 20%, 50/50 castor and synthetic.

For years I have been using the Omega 25% in my control line (added castor), rc planes, rc helicopters, and rc trucks.

Last week I ran out of Omega and replaced it with a case of Sig Champion 25%.

NOTHING, I mean NOTHING runs right anymore.   The car engines would not run.  I had to turn the low and high speed out a lot and spend considerable time on each one to get it reliable.   They still do not run as good as with the Omega. 
This is disappointing to say the least.

Does anyone have an idea of why such a drastic difference?  The engines run hotter also. (30 degrees +/-)

I did this because no hobby shop within 150 miles carries Omega 25% anymore and I was forced to mail order.  The Sig was $10.00 a gallon cheaper.

Please give me some insight!

Thanks.

[mike londke]

I run Sig Champion %25 in all my 1/2A engines even my hi-performance Russian combat motors and have had no problems. My 1/2A Profi engines have hundreds of runs on them spinning up to 34,000rpms and have little signs of wear. They start easily and hold a needle. Sig is the only fuel I have run in them. Not sure what is happening in your case. If everything was fine on the Omega I would try a plug in a different heat range for the Sig fuel.  I bet Randy Smith can tell you.

[Motorman]

I would dare say any Sig fuel will be better than any Omega fuel. When you go to a higher nitro content you have to open the needle valve and you will run hotter too so, the Omega might not be an actual 25% nitro. I would never run Omega in an engine I care about.

MM

[Eric Viglione]

My comment wasn't about ultimate run quality or potential, only about the differences he is experiencing from his normal needle and fuel draw, etc. And in cold weather, it will be even thicker... I learned this the hard way back when i played with 4strokes.

[Dan McEntee]

   Omega is NOT 20% total oil. More like 17 to 18%. Contact Morgen Fuels and see what they say about oil content. Some one here on the forums has done a boil down test to verify it. Car engines run less than 18% typically. Even if you added castor to the Omega you might not have gotten to 20%, but had your engine carbs adjusted accordingly. I have been running SIG fuel almost exclusively for A LOT of years and never had a bad batch. Some I have in stock I've had for several years, but keep it in my basement in cool, dry place. Different fuels will run differently in the same engine. If you can't get dialed in on SIG, you may want to look into VP/Powermaster. You local hobby shop may oder that in for you or they may ship in quarts to make shipping and price more agreeable.
   Type at you later,
   Dan McEntee

[Motorman]

Don't car and buggy engines run 12% oil?

MM

[Skip Chernoff]

When fuel is mixed correctly all measurements are taken by volume not by weight. I'm certain that the Sig fuel is waaay better and that you need to readjust your carb settings for the Sig fuel.

[Eric Viglione]

Rusty - the Sig has waaaay more castor than the Omega, and why I said it is thicker in viscosity. Its fifty fifty castor/synth, where the Omega has a kiss and a promise of castor, and is mostly synth oil, and less total oil than Sig also. Sig also potentially has a hair more nitro, because of the way they differ in measuring. I sincerely doubt you need to add oil to the Sig if you were happy with omega. If you cut sig with some methanol, you will lower the oil ratio, but nitro goes down too. That is why I suggested getting some straight synth oil 25% nitro fuel and mixing it half and half with the Sig.... Keep nitro up, and just basically bring the oil down a tad. Ever what, as long as it works!
Eric

Yes, Skip it is true.  The engines would not run, until I richened up both high and low end when I switched from Omega to Sig.  

Does the Sig have more or less nitro than Omega?  Does Sig have more or less oil than Omega?

That is what I need to know, so I can add castor if I need to.

Thanks

[Dan McEntee]

Yes, Skip it is true.  The engines would not run, until I richened up both high and low end when I switched from Omega to Sig. 

Does the Sig have more or less nitro than Omega?  Does Sig have more or less oil than Omega?

That is what I need to know, so I can add castor if I need to.

Thanks

      Read ALL of the posts ALL the way through Rusty. All the answers are here! You obviously know how to adjust a carb and got results, so you have some idea of what is going on with fuel mixtures. A little more "fuel mixture 101" is that if you lower the oil content, you actually make the fuel mixture richer. if you do that, you have to close the needle to get the resulting RPM you want. Today's modern engines with modern metals allows for less oil. The R/C car crowd doesn't need more than 12 to 17% because they are on the throttle for such short times, and at the richer fuel mixtures, are actually running cooler. That is why most high performance racing of any kind use alcohol for fuel. It burns cooler. Ask anyone that runs old ignition engines! But the draw back is that you need almost twice as much alcohol for the same BTU return as gasoline. So to get more power, nitro was brought into the picture. This is a lesson learned by a lot of vintage motorcycle racers who try to run modern synthetic oil in the fuel for their older bikes and their carbs jetted for older gas/oil mixtures. The newer oils are concentrates usually, but offer greater lubrication so you need less oil, which means more gasoline, which means their bikes run rich and foul plugs or won't run at all. It's more or less the same for our engines with some differences. You are probably running more modern engines and the only engines your Omega would have caused problems is in older Fox, McCoy engines and the like. You say that your engines are running 'hotter" on the SIG fuel, but how to you make that judgement?  It may be that your aren't rich enough yet on the needle settings. On some R/C carbs, for those following along, some have a low speed and high speed needles. The low speed needle is for idle and up to 2/3 to 3/4 throttle. The high speed needle is just like it says, wide open on the throttle. On some engines it gets pretty tricky, but OS came up with their bleeder type carbs and eliminated the low speed settings. If this sounds complicated, try tuning some old vintage dirt bikes where you can throw in slide cutaway size, needle and needle jet size, and air mixture screw setting in along with pilot jet, main jet and oil/gas ratio! When you start getting the SIG fuel dialed in, you may find you will need to play with props a bit on some engine/plane combinations. It just takes some patience, and listening to what your engines tell you what they require.
  Good luck and have fun,
    Dan McEntee

[Dan McEntee]

   I wouldn't live or die by the temp gun, go by how your engines sound and check your glow plug every now and then and by how your exhaust looks. They may be running hotter but not excessively hot. Castor oil doesn't really burn, and helps carry heat out of the engine. You may actually be making more power with the SIG fuel, and  you may be over pitched on props of some planes and causing them to heat up. And the way it's mixed, maybe less nitro. Just something you'll have to work through. Just make one change at a time.
     I wasn't an MX guy but raced enduros, cross country and observed trials back in my younger days. These days I like to fix up old enduro bikes and love ISDT type stuff and vintage trials. I raced the ISDT Renion Ride for 10 or 11 years straight before some other family responsibilities took over. I have a 400 and 250 Penton in my garage waiting to get finished rebuilding, and some CanAm, Huskies, Hodakas, a Rokon and 250 Hercules in the stable also.  You can time me with a sundial on the MX track, but put me in the woods and that's where I'm most comfortable and fastest. I would like to think I have a few more races left in me yet!
   Type at you later,
   Dan McEntee

[bill bischoff]

FWIW, morganfuel.com says Omega 25% is 17% oil content, 30%/70% castor/ synthetic mix.

[john e. holliday]

If you lived close enough I would take your SIG fuel.

[Brett Buck]

John, I wish you did.  I will probably never use it all. 

   The most obvious difference is the fact that that the SIG is really 25% and the Omega is something like 17% or so. Thats in the range of putting you over the top on compression, depending what you are doing. SIG, as a general rule, is a much higher quality fuel than Omega, but the engine will tell you what you need to know about it.

    Brett

[Steve Helmick]

Metal is good. Some plastic jugs are not so good. SIG jugs were NG for awhile, but presumably, they fixed that. I've got some plastic 5 gallon race car jugs that aren't very good for long term storage.  Steve

[Chancey Chorney]

Why, yes you can! (no pun intended) 

Check out this thread. There are a couple of places listed throughout. Post # 1 and #4 for starters.

[Brett Buck]

Brett, what it boils down to is that I am too damn dumb to figure out what it is.  It isn't worth me ruining all my rc truck engines, especially the OS.  They are expensive.  My guess now is that maybe the engines would need another head shim? 

The strange thing is that you can tune them to have good power, but they smoke like Cheech and Chong AND run very hot, right at 300 degrees, which is too much. 

I have no issue with Sig.  It is apples and oranges to compare the fuels.   Sig tech support is good guys.

Can you tell me if it is safe (what kind of container) to keep fuel inside the house.  Unopened gallon jugs.  I am going to have more fuel than I ever had and it is too hot in the garage 99 degrees during day. 

    I wasn't going to tell you to do anything different, just suggest an area for exploration if you were interested. I don't use SIG fuel anymore, either.

      It's probably as safe as most anything else to store. I prefer fuel in cans,  but in reasonably temperature-controlled environments, jugs are usually OK. You *do* want to keep it in the dark.

     Brett

[Jim Kraft]

I think one of the big differences is that most fuels that say castor synthetic mix may be only 5% or less castor. Sig fuel that says 50 50, is half of each. Mucho difference. Makes big difference in needle settings. Cool Power is all synthetic. Not sure what Omega is but I am sure it is not half castor. May be only 3%. Castor synthetic mix means zilch without knowing the percentage of each.

[GallopingGhostler]

If you lived close enough I would take your SIG fuel.

(Adapted from Apocalypse Now): You smell that? Do you smell that?... Nitro, son. Nothing else in the world smells like that. I love the smell of nitro in the morning. You know, one time we droned a hill, for twelve hours. When it was all over I walked up. We didn't find one of 'em, not one stinkin' dink electric. The smell, you know that methanol smell, the whole hill. Smelled like... victory. Someday this cylinder liner's gonna wear out...