Is engine braking harmful?

This is a question for the more mechanically inclined/experienced here. It could apply to any of the newer technology engines we are seeing these days, including the Cross 2.0L....

Is it harmful to the motor or drive-train to use the engine for braking while descending long steep hills?

Of course it saves wear and tear on the brakes, and you don't want to overheat them. I was told by a mechanic many years ago when I asked him this same question, that it actually could be helpful. His reasoning was, it creates a vacuum in the upper cylinders, and that pulls a little oil up past to the compression rings, which could always use a bit of extra lubrication.

Now that was likely the case for motors in the 1980's, but I wonder about todays "loose" engines.?. I do lots of mountain driving, and it's really a must to keep from trashing the brakes in 20k miles. But is it OK on the motor?

Over reving the motor is never a good idea, but I'm talking about downshifts that take it up to a sustained 2-3k RPM.

Dave O.