The cold startup smoke sounds like valve seals. The reason there won't be
any smoke after the engine's hot is the cat burns off the smoke. That's why
you don't see many smoky vehicles these days. It could also be worn valve
guides (the part the valve rides in).

It might be worth pulling the valve cover and making sure the oil drainback
holes are clear. If oil collects on top of the head because the drainback
passages are clogged, that could make the seal problem worse. Even good
valve seals will have drainage if they're immersed in oil.  

With the valve cover off you can get a handle on how well maintained the
engine was too. If the oil changes were infrequent, you'll often see sludge
buildup. What do the spark plugs look like? They'll tell you if you're
burning oil too.

I'd switch the PCV valve as a matter of course. It's a disposible tune up
item anyway like plugs and wires.  

When the car is started after sitting a while, it does emit a lot of
smoke.  The smoke does have a blueish tint, but I would say it is more
gray than blue.  Other than this, no, there are no leaks, and the valve
cover does not significantly leak, althogh there is a trace amount of
oil on it.

I personally think that the car has all the power it should for being
its age.  It still climbs hills beautifully and never overheats.  The
heater and air conditioning work great.  I have never noticed leaking
on the ground where I have parked it.

All the above information was all that went into the original
diagnostic about maybe having a bad valve or valve seal.

I have been monitoring gas consumption since I bought the car.  I drive
probably 90% of the time on the highway (about 400 to 450 miles each
week) and I have averaged 32 to 34 mpg.

Now that you know more about the situation and the distinct burning
only at cold start-up, what do you still think?  Is it the PCV valve?
I hope so, because that sounds like the easiest and cheapest fix.

How much diagnostics actually went into identifying the valve as the
problem?

Does the engine seem to lack power or otherwise sound odd? I know that may
be hard to assess with a new used car, but give it a shot.

Are you seeing oil drips beneath the car when it sits awhile?

I would first do a complete tuneup (genuine Honda parts only for plugs,
ignition wires, distributor cap and rotor, and PCV valve); new air filter
and fuel filter. Drain and fill with genuine Honda coolant or the orange
Havoline Dexcool the cooling system. Purge properly of air. Check and adjust
as needed the ignition timing.

That's around $200 of parts and labor. Do not go cheap on the parts: Buy OEM
(= genuine Honda) as directed above. This $200 is an investment. These items
need to be done every few years anyway.

See http://home.earthlink.net/~honda.lioness/id11.html for an overview of
the tuneup above.

I would then monitor the oil level. Make sure it's not leaking from the
valve cover or into the spark plug tubes: Check the exterior of the engine
right beneath the valve cover; check the spark plug tubes once a week for
the immediate future. Report on what you see. There are certain seals that
certainly may need replacement for a car this old.

Look for oil drips on the floor beneath the car, and try to identify from
where they are coming.

A bad PCV valve will cause excessive oil consumption. The good news is it's
only about a $20 part and most people can change it out themselves within
five minutes (an hour if you're new to this).

Also, start monitoring the gas consumption. Measure mileage between fillups,
divide gallons at each fillup with miles driven. Report back after four or
so fillups.

Elle
Original owner, 1991 Civic LX, 174k miles. Runs like a top. 40 mpg most of
the year.

I am a new to the "honda owner family."  I bought a used Honda Accord
LX with 165,000 miles on it two months ago.  I have since noticed,
unfortunately, that it is burning about one quart of oil between every
time I fill up with gas.  A mechanic told me it was probably an old
valve that had gone bad.  He did not quote me a price for repair, but I
can imagine it will be expensive.  What do you all think?  With my
Accord being 12 years old and having 165,000 miles, would it be worth
it to get the valve replaced just to avoid the nuisance and potential
hazard?