Then there's your culprit: Worn rings.
Because modern oil combusts very cleanly, it takes quite a high level of
consumption to cause deposits on the plugs.
Are the deposits sooty with a bit of an oily feel to them, or are they
actually covered in liquid oil?
They are much closer to sooty with an oily feel than they are to
looking liquidy. E.g. they are nowhere near as liquidy and bad as the
"oil fouled" plug shown at
. Do you think this matters?
Like I wrote, the ceramic part just beneath where the spark occurs is
black-ish, sooty-ish on three of four of my Civic's plugs. Where the
spark occurs is a textured brown, like some deposits are accumulating
there, but they're not black (yet?). I figure this is because 1/2
quart every 600 miles or so is not a lot of oil burning. A concern,
but it could be a lot worse.
I should have wrote my theory now is that it is either the oil control
rings /or/ the valve guides that are going. I have looked into
replacing the valve guides but assuming I wanted to gamble that it is
the guides and not the oil control rings, it seems cheaper to just buy
a new head. I think I'd consider a new used engine from a reputable
used Honda engine seller, first.
Since you have resigned yourself to possibly replacing the motor in
the distant future, try experimenting with heavier oils (20W50, 20W40,
10W40). Looks like you have nothing to lose. 1200 miles per quart isn't
great, but its not that bad. At least it isn't 500 miles per quart. Try a
20W50 oil for 2000 miles and see if the oil consumption is reduced. Try
what the other person said, which was a 10W30 oil and the additive
I wonder if that stinkin' dealer just dumped in the cheapest 20W50 or
straight 40 weight oil he could buy, and told you it was Mobil synthetic.
Yes I think this is definitely worth experimenting with a little. I
will probably give the Mobil 1 a chance for another six months, then
try a heavier oil.
I will research the CD-2, thanks.
Yes it is something to wonder about. It was a new car (Nissan) dealer
who of course flips trade-ins. They explained they rarely took such
old cars and sold them off the lot. It could have been the original
owner who possibly added something. Either way, ISTM when a car has
more than say 150k miles, it is all about buyer beware, no? Even with
a 1-owner car. Maybe this is why new car dealers rarely deal (as far
as used car sales on the lot) with cars more than ten years old,
except to auction them elsewhere.
Fortunately, very worst case, if this car should suddenly die on me,
no big deal. I will go chase down another used car, this time more
carefully researched. Though I think it is unlikely it will die; it
really does run well, and I am on top of its maintenance. Meanwhile I
will run some "experiments" as we are calling them at this point and
try to learn more.
Thanks for the input.
I agree. Just use the highest viscosity the manual recommends for
your temp range and keep a few bottles in the trunk. Just keep
checking it once a week and add as needed. I actually think 1200 miles
per qt is fine for a car with 190,000 miles. If it doesn't make it to
a quarter million, it won't be because of this oil burning problem
(unless you run it dry).
A lot of auto maintenance sites (not just random people posting) state
that either the valve stem seals or the valve guides may be failing. I
understand what you're saying but it is hard for me to say from the
Civic shop manual drawing whether a new, properly installed valve stem
seal alone will ensure no leakage in this area.
Regardless, for now I am going the route of trying to clean things up
with continued use of Mobil 1 and/or maybe Auto-RX.
1. your honda valve guides are not submerged.
2. it's been known for internet "experts" to be full of it.
3. i've experimented with /no/ seals - you lose a little, but it's not a
massive source of loss.
unless it's lost flexibility, is worn or cracked, it will.
It doesn't matter. Oil is being flung all over the inside of the valve
cover. If your guides are worn and your seals are worn, oil will be
sucked in through the intake guides.
True as well. I've had engines that did not even use valve stem seals
(Jensen-Healey 2.0L Lotus 4 cylinder) and others that only used them
on the intake valves. However, when you say "you use a little," that
might add up to a lot in the eyes of some people. For a new engine
with minimal valve stem to valve guide clearance, the loss will be
small. However, for an older engine with worn stems and guides, the
loss can be significant. In the old days this was still trivial in
many cases. However, with modern engines, severely worn guides can
casue several problems - excessive air leakage will screw up the PCM's
calculation for fuel delivery and excessive oil consumption can damage
a catalytic converter.
New seals will help, but becasue of the excessive play, they won't
last as long, and they will still let more oil past than seals on
unworn guides and stems. Seals have to allow some oil past to keep the
valve stems and guides lubricated, so they aren't perfect seals by
If the engine is only using a half a quart per 600 miles, I'd just
drive it. With 197,000 miles on the engine, it is not just the valve
train that is worn.
IMO, it's also possible that the rings are merely gunked up with carbon
deposits. (Barring abuse, a 200K Civic should be far from worn out,
right folks?) If so, it might be possible to clean the gunk and free
the stuck rings, allowing them to resume normal service.
Does the engine have any sludge, or other signs of over-stressed oil?
I'm not a big fan of oil additives, but AutoRx seems to be a legitimate
product that actually works. It's a mix of esters that are quite
effective in cleaning up sludge and carbonized oil from your engine.
Or you might try running a good synthetic for a few changes. Pick one
with a close spread of viscosities, ie. 10w-30. Such an oil should have
fewer volatile viscosity index modifiers; these VII additives are
supposedly one of the main sources of engine deposits. Over on BITOG,
M1 10W-30 high mileage mix has a good reputation for cleaning, but any
good 10w-30 Syn should help. If you really want to clean the car, run
Redline. It's ester based, VII free, and cleans like mad.
One of these options may well help, and will be vastly less expensive
and troublesome than disassembling the engine.
I have not taken off the oil pan, but during the three oil changes
since March, I did not notice sludge when transferring oil to an old
milk jug for recycling. I was under the valve cover doing the valve
stem seal replacement and of course mopped up a lot of oil in the
process. It did not seem sludg-y or particularly dirty.
I read the Bob-is-the-oil-guy thread and am researching the AutoRX
further, for one, now.
Thanks for the input.
Have you exmained the spark plugs? Differences in coating color and
deposition are tell-tales to engine problems.
If one plug is significantly different than the others, then you know there
is an issue with that cylinder.
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