Synthetic Nitro Fuel Lube

Why be limited to synthetic lube? Many think the best thing you can do for an engine is to use some castor oil with your fuel. I'm one who agrees.

Castor oil stands up to high heat better without burning off, and does a much better job of protecting an engine against rust while stored. Fox insists that there be castor oil in their fuel.

The only down side is the fact that it leaves the outside of your engine and plane more of a mess, IMHO. It is worth the tradeoff, if you value the long life of your engine.

15% oil, assuming it's synthetic, isn't a bad ratio - adding oil will reduce the performance of your fuel, but if you're concerned about your engine, more oil never hurts. As you've found, oil designed for gas fuel isn't miscible in methanol. While it's not synthetic, castor oil is never a bad choice, but recently I've been running 15% straight synthetic - Klotz KL200 or Coolpower.

I have moved to mostly four strokes and they do not thrive in a high castor environment. Many fuel makers still put castor in the fuels even though they use mostly synthetic, and four stroke users pay the price in carbon build ups on the exhaust valves. BTDT.

Unless all you fly is 2 stroke, get a bottle of Klotz KL200 at your local hobby shop if you wish to up the oil percentage. Since I make my own fuel, I use 20% synthetic and leave it at that. I also use 10% nitro, but it seems MY way of measurement is different from what the commercial fuel houses calculate the mixture. Of course I just use straight volumetric amounts and I am sure they use something else...

So where does one buy castor oil to mix with glow fuel? And do you just measure it out and add it to the fuel?

Harlan

Klotz KL-200 Techniplate Oil Quart

Because in the instructions for the Magnum 91 4 stroke they recommend 18-20% lube, mostly synthetic. Since the nitro I have is a synthetic/castor blend, I want to add only synthetic oil.

Somewhere I read that the commercial fuel quoted percentages are by weight rather than by volume. I don't know how big the difference is.

"H Davis" wrote

I got mine at a hobby shop, when the fuel that they had did not contain any castor oil, and I have a Fox. (castor required, according to Fox)

I just add about 4 ounces to the gallon, and it seems to keep all of my engines happy. I know that it is probably more than is required, but I'm not racing, or trying to wring every last ounce of speed out of them. I like the long lasting idea, when it comes to my engines.

Tower has it:

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Volume changes with temperature. Weight does not.

Ed Cregger

I got some Klotz synthetic at the hobby shop and it mixed well. It has both SIG and Klotz on the label. there is more than 1 kind of Klotz synthetic. One mixes with alcohol, the other with gasoline.

Ed

Of course, and I imagine that Marlowe knows that.

It's more likely that alcohol, nitromethane and oil (whatever sort) have different densities, and a difference would come from that. If the densities differ signifigantly, then the difference between `20% by volume' and `20% by weight' WILL become signifigant.

Of course, I can look all this up ...

nitromethane, 1.138 g/cm^3 methane, 0.792 g/cm^3 castor oil, I can't look up, but it's probably less than 1 g/cm^3

So, it looks like it does make a signifigant difference, though when you're just adding oil to your fuel, you're probably just eyeballing it anyways and a 20% error probably isn't signifigant.

As for changing with temperature, all of the components of your fuel are likely to change volumes similarly (not exactly, but similarly) with temperature, so the percentages by volume probably won't change signifigantly even with large changes in temperature.

A final note:

I purchased a quart of Klotz KL-200 at my LHS and added it to my 15% glow fuel to bring it up to 20%. It is good 4 stroke break in fuel. Thanks for the info from the group.