Oil percentage

[Matt Piatkowski]

Hello,
Is the oil percentage given by different glow fuels producers given in % of volume or weight?

I am usually buying the Morgan Omega 10% nitro that, according to the Morgan Fuel web site has 17% of oil.
50% of this 17% is synthetic oil and another 50% suppose to be castor.

Say, I have a gallon of Omega 10% nitro and would like to bring the total oil content to 22%.

How much castor do I have to add to this gallon by volume?

Thanks,
M

[Tim Wescott]

If it's truly by volume add a cup of castor per gallon.  In theory you'll have 21.88% oil.  In truth you'll be plenty close enough.  When I was doing this there was enough free space at the top of the bottle that I could just add a cup to the gallon and give it a shake.  I was probably doing horrible things to the amount of head room available for expansion or some such -- so I made sure to go out flying as soon as possible!

I currently order cases of PowerMaster GMA mix, but if that falls through I'll go back to Omega + castor, or I'll mix my own.

[Steve Helmick]

I wouldn't be shy about emailing Morgan and asking if they measure by volume or weight. I'm pretty sure it's weight, however. That means their 17% is really about 14% by volume. Your RO-Jett may prefer that you add Klotz instead of castor, by the way.

Tim...does PM still come in metal cans? If they changed to jugs, then 4 gallons per case? Or still 6 gallons/case?    Steve

[Tim Wescott]

I wouldn't be shy about emailing Morgan and asking if they measure by volume or weight. I'm pretty sure it's weight, however. That means their 17% is really about 14% by volume. Your RO-Jett may prefer that you add Klotz instead of castor, by the way.

Tim...does PM still come in metal cans? If they changed to jugs, then 4 gallons per case? Or still 6 gallons/case?    Steve

6 gal/case, metal cans.  I have a lifetime supply of fuel tank stock.

[Brian Hampton]

It makes sense to me for a reputable manufacturer to mix by weight IF the desired result is to get a specific volume at the standard temperature of 59F. Weight (mass) doesn't change regardless of temperature. If this is how they mix fuel then it also makes sense to label by volume because that's how fuel has traditionally been mixed at home and is well understood.

[Steve Helmick]

It makes sense to me for a reputable manufacturer to mix by weight IF the desired result is to get a specific volume at the standard temperature of 59F. Weight (mass) doesn't change regardless of temperature. If this is how they mix fuel then it also makes sense to label by volume because that's how fuel has traditionally been mixed at home and is well understood.

Absolutely correct on both points. But oil and nitro (not that you'd know about that stuff!) is much heavier than alcohol and also much more expensive. There seems to be a tendency to advertise a percentage number but not say whether by weight or volume. As you say, volume is the tradition, and there is quite a difference between what is implied and what is assumed. They aren't lying, exactly, but if it runs like chit, they may as well be. Eventually, either the word gets out or people go to another source.  Steve

[RandySmith]

It makes sense to me for a reputable manufacturer to mix by weight IF the desired result is to get a specific volume at the standard temperature of 59F. Weight (mass) doesn't change regardless of temperature. If this is how they mix fuel then it also makes sense to label by volume because that's how fuel has traditionally been mixed at home and is well understood.

It  make  NO sense  to mix by weight and then tell people it is by volume.. it would make perfect sense  to state on the label it is mix by weight  and  NOT volume. it does matter.  I have seen FOX 35s, OS 35S and McCoy engines completely wiped out in one run by cool fuel that was really 14% oil. Most everyone knows now, but there are those who still have major run problems with fuels that they assume,,incorrectly.. is mixed by weight, and they think 20% oil means 20% of the volume is really oil.

Randy

[Terry Caron]

I think Morgan oil content is 70% synth/30% castor Matt.

This is a handy calculator for adding oil - plug in a few numbers and it does the math for you.
http://www.nitrorc.com/fuelws/oilonly.asp

Randy - is there a simple conversion factor for weight vs volume or not so simple?
I use Morgan Omega also and asumed 17% oil meant volume.

Terry

[RandySmith]

I think Morgan oil content is 70% synth/30% castor Matt.

This is a handy calculator for adding oil - plug in a few numbers and it does the math for you.
http://www.nitrorc.com/fuelws/oilonly.asp

Randy - is there a simple conversion factor for weight vs volume or not so simple?
I use Morgan Omega also and asumed 17% oil meant volume.

Terry

Hi Terry

the last time i did a boil down test on cool fuel, it was listed as 18%  oil, test showed it was about 14.5 %  oil, this done from 100ml batch., so in that range figure 3 to 3.5%  down in volume. They are now making a CL  fuel, it could be that mix has more oil in it??

Randy

[Paul Smith]

If you deal with Ritch's Brew you can get a straight answer.  And I trust that Randy's answer will be measurement by volume. 

As mentioned by others, the weight system is used to sluff off low grade fuel with less oil and nitro then the buyer believes.

Whenever I tweak fuels I use my own 100 ounce method.  I set up an Excel spreadsheet with the ounces of each component per 100 ounces of fuel.  Then I can tweak the percentages based on adding ounces of oil, nitro, or methanol.

I measure the fuel with a big graduate cylinder, which is easier that weighing it on a scale.

[Terry Caron]

Thanks Randy - a website check of their Omega blends shows all to be 17%, 70/30 synth/castor except 4-Stroke 17% (50/50), Heli 17% (99/1) and yes, Control line 22% (50/50) in qts only.
Control line blend's new to me.
So your oil recommendations in the pinned topics are by volume?

Unfortunately Paul, I must deal with what the LHS carries - Morgan only.


Terry

[C.T. Schaefer]

Last season I burned 3 gallons of the Omega controline blend. Worked great! Dismayed when they decided to sell in quarts only. Will mix my own from now on.

[Terry Caron]

I just got back from my LHS with 2 gals Omega 4-Stroke, and they didn't have Control line (no surprise).
I have a couple gals of castor and, since most of my fuel goes through older engines, the 4-Stroke will give me less synth in my mixes.

Terry