I have some RC car fuel it is Traxxas 20% Nitro...I know this fuel only has about 8-12% oil in it..Can I add castor oil to it to make it 18% and run it in my plane?

Thanks

Yes go for it

No authority on this but how will you know when you have added what amount needed? also 20% nitro is a lot for most planes. Perhaps an authority will give you better answers good luck.

It is a simple volume percentage, pretty easy to figure out how much you need to put in based on how much is there already.

Some basic math will allow him to figure out how much oil to add. Adding oil will also slightly reduce the nitro percentage compared to the total volume. Some engines actually LIKE the extra nitro and since he didn't state what engine it was destined for we will need to let him decide that issue.

There's 128 fluid onces in a gallon

You can work it out by ratio and proportion

OK,
Resurrecting my ME degree...

Here is an equation to add the correct amount of oil to the fuel you already have to get the desired ratio of oil in the fuel. The definitions are as follows:

P1 (The original Percentage of oil estimated in the fuel)
P2 (The desired percentage of oil in the fuel after mixing)
V1 (The original volume of fuel you are starting with)
V2 (the volume of oil you need to add to the fuel to get desired percentage (P2))

V2 = ((P2 - P1) x V1) / (1 - P2)

If you add V2 to V1 and then divide it by the volume of the Nitro originally in the fuel(V3) you can find the new % of Nitro (P3)

V3 = .2 * V1 > .2 = 20%
P3 = V3 / (V2 + V1)

Gotta rest the hamster now.
Curtis

I can calculate the ratio...and I looked in the manual it says 5-20% nitro recommended...

so if i'm figuring this correct, i have a gallon of wildcat fuel, 10percent nitro, and 16 percent oil, (80 syntheic, 20 castrol) in order to bring the oil up to 20 percent to break in a saito 125, i would add 5 oz of castor? would that lower the nitro to low?

It would lower the nitro but it would'nt be too low

great, thanks

It's a common misconception that adding oil reduces the nitro content. It only does this if you're using the total of oil/methanol/nitro. The engine only runs on (and is tuned for) the flow of methanol/nitro through the needle valve. Adding oil doesn't change the ratios of methanol/nitro in the total fuel mix. Put it this way, if you had a fuel with 10% oil, 45% methanol and 45% nitro then the ratio of methanol to nitro is 1:1 (or 50/50 if you like). No matter how much oil you might add to that mix the ratio of methanol/nitro will never change.

I guess that is how you end up with 110%.

We have a guy at our club who does this all of the time with buggy fuel, buys a gallon and buys a gallon of methanol at the local hardware store, then adds castor, worked good for him all last year