New 2 stroke outboard motors!

[fourdfish]

Now you are saying something different!

Actually the oil in the ETEC is not sprayed into the combustion chamber above the the piston but below it! It is never mixed with the gas and the very tiny amount left on the cylinder walls is of course completely burned. You cannot detect this and tests show the result is extremely clean. 4 stroke engines do the same! Some tiney amount of oil is always left on the cylinder walls.

[Fletch]

Direct Injected two strokes put raw fuel directly into the cylinders. For all practical purposes, there is no oil mixed with the fuel prior to it entering the cylinder. In 2 strokes of old, the fuel (and air) flowed through the crankcase before reaching the cylinder. Oil had to be mixed with the fuel to provide lubrication to the crank and rod bearings. In a DI 2 stroke fuel does NOT flow through the crankcase. So to provide lubrication, oil is directly pumped to crank and rod bearings and other critical parts via a dedicated oil pump just like in a 4 stroke. The big difference is that DI 2 strokes continuously get a diet of fresh, clean oil (not filtered and recycled like in a 4 stroke).

As far as DI's consuming oil is concerned... Yes - they do burn oil. 2 strokes breathe through the crankcase. The air used in combustion is flowing through the crankcase and lubricating oil gets swept up in the air flow as it makes its way to the cylinders - especially at higher rpms. For the most part, this is where the bulk of the oil "burn" takes place. I was also told by a reliable source that ETECs send a very, very minute amount of oil to the fuel injectors. It is not sent to mix with the fuel for lubrication purposes. It is sent there strictly to keep the injectors clean. We are talking about a very miniscule amount of oil here. I'm not sure if other DI motors do this or not.

We should not forget that oil is a petroleum product just like fuel. In modern DI 2 strokes, the oil formulation provides for a very, very clean burn. Some DI 2 strokes have lower emissions than equivalent 4 strokes. They do this even though they are "burning oil". Yes you will add oil to a DI 2 stroke more often than you will in a 4 stroke (depending on the brand/hp though it can be very close). But, you also won't have any dirty oil or filters to dispose of either. So each has its pluses and minuses.

[MTRiverRunner]

wingnut,
they are right. In a Direct Injected 2 stroke the oil is injected directly where it counts. The E-Tec can even inject oil directly onto the wrist pin (really cool and efficient technology). Since the oil is put where it is needed very little is needed. THe little bit that is actually injected is eventually picked up by the air that flows through the crankcase into the combustion chamber where it IS burned. THe difference is that the oil never reaches the fuel, when it reaches the combustion chamber it is atomized in the air and thus burns completly. Actually, if there were oil in the fuel it would do absolutly no good, since the fuel never goes through the crank case on a DI 2 stroke. It is injected into the cylinder under high pressure. The fuel is "Directly Injected" into the cylinder right after the exaust valve is covered by the piston, It never sees the crank case in it's path from the fuel tank to the combustion chamber.
I think that you may be getting confused with some old 2 stroke technology called Oil Injection. Oil injection simply meant that you didnt have to mix your own oil, the oil was injected into the fuel immediately before it entered the crankcase. New 2 stroke outboards, are drastically improved over their old bretheren. They are for the most part the most advanced engines in the world today. It is my humble opinion (opinion only) that they are better than 4 strokes in every category except that they are a little louder.