I have a new engine on my plane, specifically an O.S. 46AX. This may or may not be problem, but the oil on the side of my plane is a dark brown, not a nice clear pink. I've been told that this is normal for a new engine. Is this true? Talk to me.

Does not sound normal. Dark colouring usually means either metal to metal rubbing (dark grey to black staining) or dark brown to black, which indicates that the oil is burning (carbon staining). It is likely you are running too lean/hot and on a new engine this is terminal. Follow the manufacturers instructions, use the run-in fuel recommended, and if you are unsure get help from one of the club members whose engines always start, never seem to need ground needle tweaking, are still running when the model lands, and still runs funny old engines he purchased years ago.
Evan, WB #12.

If your talking about the oil residue that gets on your airplane that you clean off before you go home, That is normal. Your engine wont spit out nice clear pink oil, like the color of gas you put in, Once it burns in the engine and spits out the muffler it just comes out as a darker burnt color. The only time you need to be concerned while running glow fuel is if your engine is not spitting out this oil residue, then you might be having some problems.

mt 46AX spit dark oil for a couple of galons when it was new, towards the end of the last gallon it began to clean up a bit, another thing you wil notice is the new plug will foul after the first few tanks, this is normal its because of the micro metal fragments that get into the plug durring the break in process,tend to break the plugs down,after the #3 plug that comes with it fouled, I switched to a #8 its been in there ever since, as long as your running a little rich your good to go.

That's normal, it's usually a gray but being color blind I could be wrong about that. It's just the parts in the engine wearing in, it goes away in a while, until the engine starts weraing out!!

Rub a little oil between your finger and thumb. If you see silvery flakes, that's BAD. That's aluminum from the inside of your engine and shows it's very lean. If the exhaust is black or almost black, that's bad. I light brown is ok.

Hi Idasam
I have broken in many OS engines, including two OS46AX and never noticed dark exhaust residue. I would contact OS.

If you're using after run oil it could just be that blowing out initially. I get some brownish residue from it right at startup.

Check your muffler bolts. If the bolts are loose you will get a dark brown (usually black) color to the exhaust residue. This is caused by the muffler rubbing against the engine exhaust port. The USED TO provide a gasket that went between the muffler and the engine. I don't know if they still do or not, but in any case, it would not hurt to make a gasket from some gasket material (or in a pinch, some cardboard that come in new shirts) and install it.

as long as the exhaust slime is clear you should be fine.... if it dark grey or almost black, not clear and has more staining properties than your average glow fuel exhaust slime, then it coluld be bad, or just a loose muffler bolt