RE: Oil content for break-in
 

LOL, so many opinions! I'll throw mine in too. :) I thought the term "de-gummed" simply meant the oil was from the first pressing of the castor bean. Apparently, there are multiple stages the bean goes through before they have extracted all they can and like good olive oil, the best stuff always comes from the first press.

All I know is my fuel has a couple percent castor in it and I wouldn't have it any other way. :)

RE: Oil content for break-in
 

You can do some online research on castor oil if you wish. I sure did and what I've learned is its difficult to get the straight scoop or atleast a consistent one. But one thing that became clear the AA Baker's standard is not a highly refined grade. Its also known as Pale Pressed and even that has variables depending upon the source. The main thing to avoid is a high moisture content and most grades don't have much anyway.

Apparently modern refining processes include additives to minimize or enhance the acidity. Some of these may improve it from a laboratory standpoint but can diminish the oil's lubricating properties. So far, I cannot tell any difference in the (Sig Baker) AA and the Pale Pressed grade that I've found. From what I can gather the oil found at the pharmacy will work but its unnecessarily expensive to get it there.

I'm using Wildcat Premium 15% Nitro 16% Oil (80/20) with 6 oz of Castor added to the new gallon. (This fills it right up to the base of the neck on the bottle.) The result is around a 14.6% Nitro 20% oil blend with a good portion of that oil being castor. This meets with the recommended brake-in fuel for my Magnum XL 91 RFS engine. And the thing runs fantastic.

Now, after I get 10 gallons thru it I may just buy the 18% oil fuel when I can find it but to be honest, I kind of like the blend I'm using just fine. And its readily available at my LHS whereas the 18% oil content fuel is less consistently available.

I will say the castor is messy but its that "mess" that lets me know my engines getting good lubrication too.

Regards,

Clay

RE: Oil content for break-in
 

The bottle I have says nothing about how it's pressed, and has no other ingredients other than 'castor oil'. It's pharmacy brand.

Another question (semi-unrelated): The manual says not to add after run oil in the carburetor. Where do you add it?

RE: Oil content for break-in
 

When I'm cleaning the belly I stand my plane up on the spinner. While there I shoot some oil up the exhaust. Sometimes when I flip it over I drop some in the carb too. Then just hold the plane at an angle friendly to let the oil run into the engine and turn the prop several times. To make certain the oil was pulled in I hold the plane so as to drain the exhaust. Usually, nothing comes out which tells me it went as intended. I also try to turn it while inverted to lube the rockers.

Clay

RE: Oil content for break-in
 

It's fine to add after run oil to the air intake on the carb. While it's kinda poorly stated in the manual, what they mean is that you shouldn't add the after-run oil thru the carb's fuel fitting. That can cause the needle valve o-ring (if equipped) to swell, causing trouble in the future.

Adding thru the wide open throttle barrel is the best way. Personally, I turn the engine so the rotary valve is closed (look down the carb throat and turn the prop, you'll see!). Then I almost fill the carb with after run oil, and then turn the prop over a few times to get the oil into the engine. It gets sucked in just like the air does normally. This method gives you a decent sized "measuring cup" that varies with engine size, pretty much assuring that a decent amount is added.

J

RE: Oil content for break-in
 

JBurry- Thanks that makes sense now that I think about how they worded it in the manual w/reference to the ring.

I asked Hobbico about castor oil this is how it went:

Me:Hello I just purchased an OS 46AX, and have a question regarding lubrication. I have fuel that is 15% nitromethane, and 18% synthetic
oil. I have read in many places that castor oil is the best for the engine, especially during break-in. I have a brand new bottle of
castor oil from the pharmacy, and am wondering if I should add some to the fuel. If I were to add the whole bottle to the fuel I have, it
would create a blend that is 22.8% oil (30/70 castor to synthetic) and 14.1% nitromethane.

Do you suggest I use the castor oil for the break-in period, or just
use the fuel with synthetic lubricant?

Hobbico (OS):
Joe,
Thank you for your recent e-mail. It is a good idea to use a castor/synthetic blend but it's not required. If you add that much castor it will allow your engine to run a lot cooler but you will loose some performance. If you have a lot of experience running engines then you would probably be ok to run just synthetic but if you don't, running castor will help prevent overheating.

RE: Oil content for break-in
 

Castor oil's great benefit is that it's got a higher boiling/decomposition point than the synthetics do. It adds what we call "lean run protection". Our engines are, of course, lubed by the oil in the fuel. As we lean a mixture, besides the engine gaining power, it also begins to loose lubrication, and make more heat. All this becomes critical at some point, and the heat of the engine's components is enough to begin burning oil as well as fuel. Synthetic oils burn off about 50 degrees lower than castor does, and it burns pretty cleanly, leaving little behind in the engine. Metal to metal contact occurs, followed quickly by seizing. When castor oil approaches it's temperature limit, it doesn't burn cleanly. It forms a slick varnish coating on the hot parts. This provides some degree of protection to the metal, and while the engine stops, it is likely to sustain less damage in doing so.

This is also why castor leaves planes dirtier than synthetic does. Some of the synthetic oil is always burning, and burning oil's useless to your engine. Oil that comes out the pipe and slimes your plane lubed the engine first.

Synthetic oils are entirely adequate so long as the engine isn't leaned too far. That's why we tune an engine by first leaning to peak RPM's, and then riching it to fall about 2-400 rpm below peak. Keeps combustion temps in line, and some (enough) of the oil survives the process.

J

RE: Oil content for break-in
 

I'd go with what the manual says... I'm silly like that...:D