-----------------------

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Sorry, Elle, I should have given you points for being HALF-RIGHT. The
PCV valve can get PLUGGED (which is what you described about the
pressure increase / leaking seals) or it can go OPEN, which sucks oil /
fouls plugs / wrecks CAT. Stuck open can also shoot the mileage to HECK
because the computer compensates by altering timing / richness when it
won't idle correctly. Some would argue it can screw up your emission
tests too. :-)  

We dont' have that here so I'm no expert (about anything, actually :-) )

'Curly'

I'm glad you posted. I was trying to remember whether the reason behind high
oil consumption with a failed/failing PCV valve was oil vapor in the
crankcase being sucked into the air intake at an extraordinary rate and so
burned, or whether it was the high crankcase pressure pushing the oil out
the seals. Another poster contended what you said, as well. I suppose a
google check would also support this point.

So since I know Curly is a reputable regular here, and the other guy also
said it, I agree: Try changing the PCV valve.

The Bhudda poster can also do a little benchmark test beforehand: With the
car at idle, pinch shut the tube to the PCV valve. Listen for a click. It
should happen within 30 seconds. No click, definitely replace the valve.
Click, and the valve may or may not need replacement. If the age is unknown,
replace it.

Use only a genuine Honda (= OEM) PCV valve. See www.slhonda.com (under the
parts section, engine, breather tube) for good OEM prices; around $19 if one
includes shipping. One of my dealers had a pretty fair price for PCV valves,
too, so call locally as well.

<SNIP>

--------------------

Sorry, Elle, gotta disagree with you on this one. If the spring in the
PCV rusts and snaps, it will allow a free flow (rather than 'metered'
flow) of oil vapor in the crankcase to be sucked into the intake, which
means the engine can be burning the oil invisibly. Of course the CAT
will suffer, and Oxygen sensors can get wrecked too.

'Curly'

With this info, I would not bet on it being the PCV valve. This valve
normally routes gases in the (oil) crankcase to the air intake. If its
malfunctioning, what it can cause is overpressurization of the crankcase,
forcing oil past various seals, like the oil pan seal, distributor shaft
seal, or front crankshaft seal. If you're not seeing oil on the ground or a
really greasy engine exterior, I'd rule the PCV valve out.

You can replace it (or just clean it out with a spray can of carburetor
cleaner, easily found at Autozone and probably Wal-Mart), simply because
it's an old car, it's probably due (per routine maintenance), and it's not
expensive, but I don't think it's going to fix the oil consumption problems.

One final check: Are the spark plug tubes filling with oil? If not, then
whether it's a valve or worn rings or something else is now beyond my
expertise. I'd be googling and checking back here to gather other's input.

I think the smoke is a symptom of something getting into the cylinders that
is not supposed to...

Good luck. Updates are welcome.

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?