[KKA]

I've been using the normal, 5% fuel with castor oil. I picked up a jug of fuel at my lhs, thought it was 5%, but when I got home, I realized i picked up a jug of synthetic fuel. The label says 20% oil content. Will this hurt my engines or is it o.k to use.
I'm flying larger planes with a Super tigre 2300, Super tigre 2500, and a 0.91 Super Tigre in a Hanger 9 .60 size corsair.
I'm just a little concerned it will hurt the motors, since they have been running so good on 5% nitro or 10% nitro. I would go back and switch jugs, only thing is, I am an hour's drive from my hobby shop.

Kelly

[kersplat]

In the larger ringed engines, synthetic oil is ok. Butttt. A little castor oyl will save the one and only ring on the piston from being burned out on an unplanned lean run situation.

[OverTemp]

Sounds like you are confusing Nitro content and Oil content.

Nitro = Power

Oil = Lube

There is only one type of nitro, but oil comes in Synthetic, Castor, or Blends. All fuels have at least 18-20% oil content, and you NEED that much oil If you were using 5% oil before you would have an unhappy motor. Sythetic oil is very slippery, but castor is better at preventing rust. I run a blend in mine.

As for the Nitro content... some engines run well on high nitro, up to 30% (Saitos, OS), but these are usually low compression ratio engines and they still run pretty well on lower nitro contents. Some engines run best on 0%-5% nitro (Webras and most other European engines)... to run higher nitro on these requires a head shim or they will run like crap. I think your motors are closer to the OS, Saito range, but can't say for sure... never had a SuperTiger.

Hope that helps.

[Noin]

I was just in my lhs the other day and a fellow pilot I know was buying FAI fuel. I asked him why that fuel and he said that he was running a Super Tiger 3000 and it was designed to run with no nitro content, which is exactly what FAI fuel is. Thats all I know about ST engines.

As far as synthetic vs. castor, it has been explained to me that synthetic oils will burn at lower tempurature than castor and if you have a hot/lean motor and run synthetic you are risking poor lubrication for your motor. I now run a blend and I find my 4 strokes run much better on it than on straight synthetic like I used to run.

Couldn't you use another "excuse" to go to the hobby store? I know I am always looking for a "reason" to go to my LHS.

[scaleguy]

Go to your local drug store and ask for some Castor Oil or some hobby shops sell Klotz castor oil as well. just add a little to the jug of fuel you have bought and all should be fine. Your oil contet will co up a bit but better to be a little heavy on the oil content then light.

When i was running glow I used a blended formula s well. Of my 20% total oil contet about 3% of that wass castor and the rest synthetic. My Enya 120R and 155R seemed to run OK on that. And oh yah 10% nitro is tops for the larger Enya FS. They like FAI and 5% best.

[Guest]

I dont think the 2300 is like the other large ST motors...it was a common entry level pattern motor when it first came out and a number of guys were running as high as 25% in them with extra head shims, pipes etc.

Oil type...depends who you talk to. Personally I always ran full synthetic with 17% oil in my big YS motors, because of the amount of fuel they would see (up to 100 gallons on a motor)...and they stayed a lot cleaner internally. Most of the pattern guys running the ST 23, were running full synthetic as well...Cool Power etc.

As to oil content...its funny because a friend of mine was running Webras waaay back in the mid 80's in pattern using only around 10% oil without problems. YS states minimum 20% and up to 24%...yet many guys run down 17-18% oil in them and often get better performance and life from the motor.

[Flypaper]

You'd never get longer life from an engine using less oil.!!

[Mitch Cronin]

Originally Posted by Flypaper

You'd never get longer life from an engine using less oil.!!

well... maybe you could if you leaned out the one with more oil more to compensate for the slight loss of power.

A big difference, mentioned above, is corrosion protection... if your engine spends lots of time sitting still, you're far better off with castor in it, than synthetic. ...and if you do use a synthetic oil fuel.... use of an "after run" oil of some kind when you're done for the day is a very good idea.