Engine - D-13A2 1342cc durability?

Hi,
I have an 1987 std hb civic with the D13-A2 in it. It currently has 177,000
miles on it and I started running Mobil 1 5W-30 in it off and on through its
life, then consistantly since about 157,000 miles.

It doesn't smoke and uses less than a quart every 3,000 miles and has never
been overheated or run out of oil, is on original head gasket, and flew
through smog a couple of weeks ago.

Couple of questions:
1. What are the differences between the D13 engines and the EW1?

2. Under normal maintenance and driving conditions, is there an average
lifespan of the these engines? Top end? lower end? I have noticed that it
has always pinged on 87 Octane since it was new, which can't be good for the
rod bearings.

3. Anything unique about these engines, except for being underpowered, such
as a tendency for this or that to fail?

This car is part of the family and i really dig it because it never lets me
down and want to keep it that way.

Thanx,
Chris

3.