Tale of Two Versas, one has soot in tailpipe. Anything to do?

I’ve got two Versas, a 2007 and a 2010. Mechanically they are 99% the same.
The 2007 has about 120K miles, and the 2010 has about 75K.
Both “run fine” and don’t have any visible smoke out the rear.

But…the 2007 has black soot inside the tailpipe, when I stick my finger in it. It’s not oily, just kind of dry and easily cleans off my finger. I assume this means that the fuel/air ratio is too rich. Correct me if I’m wrong!

When I do the “finger test” on the 2010, it is clean. No soot.

Question: Are there some “actionable” steps to take on the older one to improve the fuel/air mix? I find a lot on the internet about how older cars get this way, but I can’t find any easy steps to improving it. For example, would replacing O2 sensor help, even though I’ve never gotten any check-engine code for it? Or should I just not worry about this, and chalk it up to age?

I would find something else to worry about, this is what’s troubling me right now.
Why does my washer /dryer turn all my clothes inside out? And how do they know when to do it? I’ve tried turning them inside out myself hoping to get them back rightside out. But nooooo still inside out. And quit laughing, this is a real life problem, Damnit !!


No. The car’s computer will fix any rich condition OR throw a check engine light.

You should start keeping track of how much oil your 2007 Versa uses. Using oil can soot up the pipes. Check the dipstick regularly, mark down the mileage when full and again when you add. A quart every 1500 miles would not be too high. BUT if you don’t check between oil changes, you could be 3 quarts low (VERY bad!!) at the next change.


@Mustangman Thanks! Yes the 2007 does need more topping up of oil, maybe about a quart per 1500, I’d guess. So the dry soot is due to oil consumption over time, you’re saying. Correct to assume that this could eventually clog catalytic converter or cause other performance problems? I assume remedies would be cylinder/piston maintenance or perhaps a “decarbonizing” oil additive treatment?

@PvtPublic – chalk the washing machine prob up to age. A younger, more nubile washing machine will treat you better, I think.

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Try adding this to the engine oil.


If the oil consumption slows down or stops, the cylinders/rings are worn.


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Nothing in a can is going to “decarbonize” that engine.

Just keep an eye on the oil level in the “sooty” tailpipe car.

There’s nothing else you can do “proactively” that makes any financial sense on this. Simply monitor the oil levels on both cars, and keep them topped off as needed.

Drive on. Worry about something else.



Yes it could. Likely you will see a P0420 error code as the catalytic convertor is slowly killed. The car will likely still run just fine even after you get that code but it will no longer pass any mandated emissions tests.

Usually either a new set of piston rings or a set of valve seals depending on which has worn out. Both are expensive. Could also be a bad PCV valve which is cheap.

As another posted, Restore might help. A bit more frequent oil changes may help as well.

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I drive a 2009 Dodge Challenger with about 175K miles on it. The engine burns a little oil in between oil changes, and there admittedly is a little “soot” on both of the tailpipes. I just check the oil regular and keep it topped off.

Am I concerned about the catalytic converters or oil that burns? No.

Why? Because the car otherwise runs just fine, and it’s 13 years old with 175K miles on the engine. If something oil related does happen…it’s probably due to age and/or mileage at this point.

I’ve got plenty of other stuff to worry about. :wink:

@Mustangman @Tester Thanks for ideas. I’ll try the Restore and see if that keeps the oil bill down. If so, it might keep my cat working longer too. Otherwise, I’ll worry less about the whole thing! Thanks Car Talk!

My early 90’s Corolla engine runs perfectly, but has some black soot inside the end of the tailpipe. I doubt that indicates a problem on your 07 Versa. Unless there’s a reason beyond tailpipe soot, me, I wouldn’t introduce additives to the equation. B/c then if some problem does occur, you won’t know if it is b/c of the additives or something else. Best to keep the number of performance related variables as small as possible.

If you want to do something anyway

  • Check for engine/transmission diagnostic codes. You could have some in memory, but not know it. CEL doesn’t turn on for every code.

  • Verify EGR operation (some newer cars don’t use EGR)

  • Verify PCV operation

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@George_San_Jose1 Thanks George. Took it to nearby auto parts store to borrow OBD2 scanner. Not very experienced with those, so couldn’t find data on EGR and PCV. Replaced PCV valve maybe 18 months ago when I replaced spark plugs (big job on these cars!). However, as you said, there was an unlit code that I pulled, P0443, the purge volume control. From what I’ve read, this prob doesn’t affect engine operation, and could be just from my wife not clicking the gas cap three times!

edit; Mustangman is right and my conclusion is wrong. If there is a too rich code it means that the oxygen sensor is working and the mixture really is too rich. An aging oxygen sensor won’t get more sensitive over time. The exception being a defective newly installed non OEM oxygen sensor which could be more sensitive than it should be. Unless it’s a Ford and the O2 sensor has gone all the way bad! Then it doesn’t detect the O2 sensor as bad. This can happen someone keeps driving it with an O2 sensor bad code to the point where the O2 sensor goes all the way bad, then the battery is disconnected and the codes are cleared. Then it doesn’t detect it as bad anymore!

Royal Purple High Mileage HMX oil claims to have a patented technology that reduces catalytic converter poisoning.

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That is complete B.S. and violates the basic federal requirements of OBD2. Where do you come up with this stuff??


And that surprises you, C’mon man do you really expect anything else? :joy: :joy: :joy:


I had a faulty O2 sensor code. I didn’t fix it. After 2 years of storage there is no longer a bad O2 sensor code although there is now a mixture too rich in bank 1 code. Now the engine runs terribly. It runs fine for the first 30 seconds or so. I assume that’s open loop. I doubt the O2 sensor healed itself in 2 years.

Which does NOT mean what you posted. You have drawn a false conclusion. Why do I say that? Because a rich code cannot be set unless the O2 sensor reads it as rich, which it did.

Codes can be set if the device is slightly of spec but not totally failed. The CEL will be removed if it comes back into spec. So yes, the O2 sensor “healed” itself since it no longer sets a code but still reads a rich condition.

It runs good for 30 seconds because the car is cold and running open loop. It isn’t likely yet in closed loop in 30 seconds. And cold engines like it rich.

@TheWonderful90s Thanks for tip on HMX oil. Come to think of it, I’ve skeptically avoided the “high mileage oils” but maybe I should reconsider that. The Restore product says just add to regular non-high-mileage oil, so it might be more-or-less the same solution.