How much castor should I add?? - RC Groups
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Mar 31, 2012, 03:01 PM
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How much castor should I add??

I have 4 gal of Morgan Cool Power(green). It's totally synthetic so I'm wondering what amount of the Sig castor should I add per gallon??
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Mar 31, 2012, 03:15 PM
Registered User
I should add that my engines are: Saito 82,115 OS 55,95AX GMS 76 Tower 75,46
Mar 31, 2012, 10:41 PM
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Apr 01, 2012, 08:48 AM
Registered User
Roger that. It does not take much. Saito used to recommend at least 20% total lubrication (or oil) in the fuel. GMS and Tower are essentially the same engine. All engines IMHO can use a little Castor in the mix. I even add it to my weed eater fuel and it runs like a champion.
Apr 01, 2012, 07:56 PM
H&H Hobbies
H&H's Avatar
A little castor goes a long way. Just enough to protect from a lean run is what I prefer. I have had fine luck with 100% synthetic in my four strokes but My teacher (my Dad) is old school and always taught me to have a little castor in the blend. That advice has always served me well.
Apr 03, 2012, 02:14 AM
jeffie8696's Avatar
I think Cool Power is only about 16% oil so adding 4oz would bring it up around 18% last time I checked.
Apr 03, 2012, 04:32 PM
Registered User
Originally Posted by jeffie8696
I think Cool Power is only about 16% oil .
Why do you think that?
Apr 03, 2012, 07:47 PM
Registered User
I remember Cooper Fuels did some testing years ago and concluded that about 2 -3 % castor helped 4 strokes without causing carbon formation, so that agrees with the other advise you're getting, that 3 ounces per gallon or so would do it.

Apr 03, 2012, 08:12 PM
Registered User
The oil content of Cool Power depends on the particular mix. There's one heli mix that's as much as 22%.
Apr 03, 2012, 08:16 PM
Mach 1
pathfinder's Avatar
Most hobby shops carry coolpower that has a 17% syn. oil content.Around here anyway.
Apr 04, 2012, 11:25 AM
jeffie8696's Avatar
From Morgans site , it states Cool Power 15% has 17% lube and since Morgans is blended by percentage of weight it comes out to about 16% versus SIG which is blended by percentage of volume at 18%.
Apr 07, 2012, 05:48 AM
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gerryndennis's Avatar
Originally Posted by jeffie8696
From Morgans site , it states Cool Power 15% has 17% lube and since Morgans is blended by percentage of weight it comes out to about 16% versus SIG which is blended by percentage of volume at 18%.
G'day jeffie,

Assuming that Morgan's does mix by weight, how do you know that the weight of the oil is 17%? Is it possible that Morgan's measure by weight but use whatever percentage of weight is required to give the same amount of oil that 17% by volume would be.

I'll do this bit in metric to make it a bit easier to understand but the argument is the same in gallons.

If I was mixing a liter of 17% oil fuel I would take 170 mls of oil and add 830 mls of methanol. 170 out of 1000 equals 17% by volume.

Now if I weighed 170 mls of oil and weighed 830 mls of methanol and then put that weight of oil and that weight of methanol in a container I would still have exactly the same thing. 17% oil by volume. This may be a much easier way to make commercial quantities of fuel so even though I was mixing by weight my product would still have 17% of the volume of the fuel being oil.

There was another fuel manufacturer that was accused of ripping people off with nitro amounts because they measured by weight, but what if the weight they used was the correct one to give the equivalent volume of nitro. No one ever answered that question.

Dave H
Apr 08, 2012, 07:38 AM
Will fly for food
Exactly, a lot of commercial mixing is done by weight, corrected for density, as it is easier to measure accurately.
Apr 08, 2012, 03:06 PM
Registered User
Are you sure they correct for density, given that the expensive parts, nitro and oil are both denser than methanol?
Apr 08, 2012, 04:37 PM
Registered User


over at is a downloadable spreadsheet for use in adding castor oil to any fuel. worth a look.

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