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Model Forum / Radio Controlled / Air Models / June 2004



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Synthetic vs Blend

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Geno - 26 May 2004 03:31 GMT
Which would be the better fuel to use a 15% Synthetic or a 15% Synthetic
Castor Blend
Carrell - 26 May 2004 03:51 GMT
Which would be the better fuel to use a 15% Synthetic or a 15% Synthetic
Castor Blend
===========================
You'll get equal opinions for either choice.

Simple safe answer - use what your engine manufacturer recommends.

Some fuel companies say use blend for ABC engines and synthetic for ringed
engines.

Magnum four strokes are ringed and the book specifically calls for castor in
the fuel or you have no warranty.  Saito four strokes are ABC or AAC and
they recommend Cool Power Helicopter fuel which is all synthetic.

I like synthetic oils.  My engine is a Thunder Tiger 61 Pro which is
ABC/ABN, and the instructions call for castor oil.  I do not run the engine
extremely lean and it runs just fine with synthetic.  The slime is easier to
clean off of my plane than when I used blended oil.
Paul McIntosh - 26 May 2004 07:34 GMT
Depends on the engine and type of use.

--
Paul McIntosh
http://www.rc-bearings.com
> Which would be the better fuel to use a 15% Synthetic or a 15% Synthetic
> Castor Blend
Dr1Driver - 26 May 2004 11:49 GMT
>Which would be the better fuel to use a 15% Synthetic or a 15% Synthetic
>Castor Blend

Morgan's, among others, recommends a blend for ABC/ABN engines, and straight
castor for ringed or lapped iron engines.  I've always followed this, and
haven't have any trouble.
Dr.1 Driver
"There's a Hun in the sun!"
Paul McIntosh - 26 May 2004 19:15 GMT
Straight castor for ringed engines?  Not likely.  They recommend straight
synthetic (Cool Power) for ringed engines.  I wouldn't recommend straight
castor fuel for anything other than old iron piston, steel liner engines.

--
Paul McIntosh
http://www.rc-bearings.com
> >Which would be the better fuel to use a 15% Synthetic or a 15% Synthetic
> >Castor Blend
[quoted text clipped - 4 lines]
> Dr.1 Driver
> "There's a Hun in the sun!"
Mike Dennett - 26 May 2004 22:06 GMT
Interesting. My preference has always been castor/synthetic for ringed
engines as well, though this is based on one particular experience. A friend
of mine and I were running an ST .35 (broken in) on synthetic and it was
unhappy no matter how much time was on it, needle fiddling etc. We switched
to castor/synthetic blend, same mfg, same nitro content, and the motor
immediately changed it's character totally, running stronger, consistently,
throttling, idling better etc.

Beats me what other factors could account for that, but to us it was apples
to apples and the difference plain as day.

As to straight castor - I agree, no way. That I would tend to think is one
of those archaic "play it safe" manufacturer's suggestions harking back to
lapped engines. Has it not been demonstrated by many knowledgable engine
people that a certain percentage of castor is sufficient to provide the
benefits without the horrors associated with pure castor?

Mike D.

> Straight castor for ringed engines?  Not likely.  They recommend straight
> synthetic (Cool Power) for ringed engines.  I wouldn't recommend straight
[quoted text clipped - 12 lines]
> > Dr.1 Driver
> > "There's a Hun in the sun!"
Dr1Driver - 26 May 2004 22:33 GMT
> That I would tend to think is one
>of those archaic "play it safe" manufacturer's suggestions harking back to
>lapped engines

Yup.  That dates back to when Fox said use their fuel or void your warranty.
Dr.1 Driver
"There's a Hun in the sun!"
Paul McIntosh - 26 May 2004 23:12 GMT
Mainly because if you DIDN't use their fuel, you would likely ruin their
engines!  They were so crudely made that they needed the 25% castor to keep
the parts from grinding together.

--
Paul McIntosh
http://www.rc-bearings.com
> > That I would tend to think is one
> >of those archaic "play it safe" manufacturer's suggestions harking back to
[quoted text clipped - 3 lines]
> Dr.1 Driver
> "There's a Hun in the sun!"
Courseyauto - 27 May 2004 02:10 GMT
We Ran all castor ( because thats all there was at the time ),in all our Mcoy
and ETA ringed  engines and never had a problem. I tried using it in a new
Saito 130 twin and it did not like it at all.  In my first YS120 i used a blend
of 3% castor and 12% synthetic and never had a problem with sticking ring or
carbon build up,motor ran for years on the original bearings and ring.  DOUg
Brian Hampton - 27 May 2004 05:53 GMT
> We Ran all castor ( because thats all there was at the time ),in all our Mcoy
> and ETA ringed  engines and never had a problem.
Agreed...we ran all castor in our ETA's, McCoy's, Doolings, MS29's...you
name it. I ran 25% all castor in my Enya 45 for more years than I can
remember and still use 25% in my ST G51. Not once have I ever had this
so-called stuck ring problem. I use all castor in my ABC, ABN and AAC
engines (all 2 strokes) because I KNOW it works.
Mike Dennett - 27 May 2004 15:11 GMT
I never had the stuck ring problem either, but the goop is certainly there.
I have had to devarnish cylinder internals before though. I quite agree with
the benefits of castor oil, but I'm pretty convinced that using a percentage
of castor is sufficient and gives you some of the benfits of both types. I
use 50/50 blend (20% total oil) in my 1/2A's and they run like a champ. I
use lower percentages of castor in larger engines.

Mike D.

> > We Ran all castor ( because thats all there was at the time ),in all our Mcoy
> > and ETA ringed  engines and never had a problem.
[quoted text clipped - 3 lines]
> so-called stuck ring problem. I use all castor in my ABC, ABN and AAC
> engines (all 2 strokes) because I KNOW it works.
David AMA40795 / KC5UH - 29 May 2004 03:21 GMT
IMHO, the 'stuck ring' problem came from lean runs that burned the
castor in the ring groove.

David

>I never had the stuck ring problem either, but the goop is certainly there.
>I have had to devarnish cylinder internals before though. I quite agree with
[quoted text clipped - 13 lines]
>> so-called stuck ring problem. I use all castor in my ABC, ABN and AAC
>> engines (all 2 strokes) because I KNOW it works.
Courseyauto - 29 May 2004 13:12 GMT
>IMHO, the 'stuck ring' problem came from lean runs that burned the
>castor in the ring groove.

>David

Castor has a lot higher flash point than synthetic oil.          we used
castor when thats the only oil for models, in ringed engines and never had a
stuck ring.  I used some Cool power 30% heli fuel which is all synthetic in a
YS 63 4 stroke and after 3 gallons the valves were totally coked up with burnt
on oil.   DOUG
Paul McIntosh - 30 May 2004 00:56 GMT
You didn't use the recommended fuel.  What do you expect?

--
Paul McIntosh
http://www.rc-bearings.com

> >IMHO, the 'stuck ring' problem came from lean runs that burned the
> >castor in the ring groove.
[quoted text clipped - 6 lines]
> YS 63 4 stroke and after 3 gallons the valves were totally coked up with burnt
> on oil.   DOUG
Sport_Pilot - 27 May 2004 15:45 GMT
They weren't crudely made!  Well OK the needles and carbs were, but
the rest of the engines were well made.  I have a Fox Stunt .35 that I
have ran 100% synthetic oil on.  Ran OK but hard to start afterward,
not that the engine was overheated, its just that the thinner
synthetic doesn't provide enough compression seal.

> Mainly because if you DIDN't use their fuel, you would likely ruin their
> engines!  They were so crudely made that they needed the 25% castor to keep
[quoted text clipped - 12 lines]
> > Dr.1 Driver
> > "There's a Hun in the sun!"
Mike Dennett - 27 May 2004 20:59 GMT
IMHO FOX engines were/are a "Curate's Egg" - meaning some parts are
excellent. Others.. well..  ;-)

My old Hawk .60 ran like a bear, er, hawk. I liked the look of the tapered
cylider fins, like that matters running-wise..

Mike D.

> They weren't crudely made!  Well OK the needles and carbs were, but
> the rest of the engines were well made.  I have a Fox Stunt .35 that I
[quoted text clipped - 18 lines]
> > > Dr.1 Driver
> > > "There's a Hun in the sun!"
Paul McIntosh - 30 May 2004 00:55 GMT
They were about the most crude looking engines I have ever owned.  That says
nothing about how they ran.  All of mine ran great, once you understood
Dukies' methodology.

If the synthetic oil was too thin, then there was WAAAAAAY too much
clearance.

--
Paul McIntosh
http://www.rc-bearings.com
> They weren't crudely made!  Well OK the needles and carbs were, but
> the rest of the engines were well made.  I have a Fox Stunt .35 that I
[quoted text clipped - 18 lines]
> > > Dr.1 Driver
> > > "There's a Hun in the sun!"
Sport_Pilot - 02 Jun 2004 15:52 GMT
The only Fox engines that required castor oil was the lapped iron
piston models.  Duke claimed that the lifetime warrenty was void if
synthetic was used on any of his engines.  That didn't mean that they
would not run on synthetic oil.  He just did not like synthetic oil. I
have a Fox Eagle from the 70's that I run occasionally on Omega fuel,
that about 30% castor and 70% synthetic.  It runs about as well as my
K&B .61 and about the same weight but can be tricker to tune. Oh,and
the finish is ugly.

> They were about the most crude looking engines I have ever owned.  That says
> nothing about how they ran.  All of mine ran great, once you understood
[quoted text clipped - 32 lines]
> > > > Dr.1 Driver
> > > > "There's a Hun in the sun!"
Paul McIntosh - 02 Jun 2004 21:05 GMT
I had an Eagle IV .74 that almost refused to run on anything but Duke's Fuel
(10% nitro and 20% castor).  Ran great on it and ran terrible on
Powermaster.

--
Paul McIntosh
http://www.rc-bearings.com
> The only Fox engines that required castor oil was the lapped iron
> piston models.  Duke claimed that the lifetime warrenty was void if
[quoted text clipped - 41 lines]
> > > > > Dr.1 Driver
> > > > > "There's a Hun in the sun!"
Sport_Pilot - 03 Jun 2004 16:04 GMT
Maybe your Powermaster was 15% nitro?  Fox does not recommend more
than 5% nitro for that engine.

> I had an Eagle IV .74 that almost refused to run on anything but Duke's Fuel
> (10% nitro and 20% castor).  Ran great on it and ran terrible on
[quoted text clipped - 54 lines]
> > > > > > Dr.1 Driver
> > > > > > "There's a Hun in the sun!"
Paul McIntosh - 03 Jun 2004 17:50 GMT
I was running 5% nitro in most engines at the time.  The only engines that
got more were my racing engines and my four strokes.

--
Paul McIntosh
http://www.rc-bearings.com
> Maybe your Powermaster was 15% nitro?  Fox does not recommend more
> than 5% nitro for that engine.
[quoted text clipped - 57 lines]
> > > > > > > Dr.1 Driver
> > > > > > > "There's a Hun in the sun!"
David AMA40795 / KC5UH - 03 Jun 2004 02:14 GMT
It is rather strange that I got a gallon of Duke's Fuel that has a
sticker on the top stating "100% synthetic".  I still have the can
with that sticker!

David

>The only Fox engines that required castor oil was the lapped iron
>piston models.  Duke claimed that the lifetime warrenty was void if
[quoted text clipped - 41 lines]
>> > > > Dr.1 Driver
>> > > > "There's a Hun in the sun!"
Paul McIntosh - 03 Jun 2004 07:32 GMT
I am talking almost 20 years ago.  At that time, it was all castor.

--
Paul McIntosh
http://www.rc-bearings.com
> It is rather strange that I got a gallon of Duke's Fuel that has a
> sticker on the top stating "100% synthetic".  I still have the can
[quoted text clipped - 47 lines]
> >> > > > Dr.1 Driver
> >> > > > "There's a Hun in the sun!"
Sport_Pilot - 03 Jun 2004 16:01 GMT
I recall buying Red Max and K&B fuel with synthetic oil when I started
in the mid 70's.  I have old magazines dated in the 60's discussing
synthetic oils.  Thats a lot longer than 20 years.

> I am talking almost 20 years ago.  At that time, it was all castor.
>
[quoted text clipped - 60 lines]
> > >> > > > Dr.1 Driver
> > >> > > > "There's a Hun in the sun!"
David AMA40795 / KC5UH - 04 Jun 2004 04:54 GMT
I purchased this gallon of Duke's in late 72 or early 73 ! ! ! !

David

>I am talking almost 20 years ago.  At that time, it was all castor.
>
[quoted text clipped - 6 lines]
>>
>> David
Courseyauto - 04 Jun 2004 13:00 GMT
Missle Mist
K&B 100
K&B 1000
Frannys
Fox
 Used them all, then started mixing our own and never used anything else.  
The high oil content for the fox stunt was needed to get a good 2-4 break,if
enough oil was not used it would run erratic. High oil content is still used in
modern stunt engines to get the correct run,these are low RPM motors and still
use over 20% oil.  DOUG
 
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