Toyota Spewing out smoke in only one place. Huh?

I have a 2010 Toyota Highlander Hybrid which has been serviced regularly according to the manufacturers maintenance schedule. At 128k miles, we noticed smoke spewing from the back of the car when descending a large mountain from 8,900’ to 5,000’ or so. Once at the lower altitude it doesn’t happen anymore. Nor does it happen at high altitude. It’s just the last part of the descent where it happens.

We took it to a Toyota dealership and they ran an oil consumption test. Found that it does burn a lot of oil. Roughly 1 quart per 800 miles or so, but otherwise runs well. They suspected a cracked piston ring was allowing oil to enter the combustion chamber, which was causing the smoke. This is further supported by a code in the computer for “catalytic converter performance below threshold”.

We’re now at just shy of 150k miles and the car is still running. But I’d like to fix it. Toyota recommended a new short block for $10,000. An independent dealer recommended a new long block also for $10,000. I don’t know what to do. But I know I don’t want to spend $10k to keep the car running.

What would you recommend I do to keep the car running for another 50k miles or so?

Thanks in advance for your help.

My thought , just keep the oil level where it should be and start planning for a replacement. Also if your gas engine is running that much plus mountain driving it does not sound like you are getting the benefit of a Hybrid .


I would never spend $10K on a suspicion.

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It would be cheaper to replace the ring than getting a new engine.If it was my vehicule,I would top up with oil or use a thicker viscosity oil.

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Ford changed the rings and valve guides in our 302 f150 in 24hrs. Was warranty job. Did they do it? I think so. Dropped off Monday and done Tuesday. 1 mechanic. 16 hrs. $1600 labor? Unknown.

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Could valve guide seals cause this, if they leak a little oil that gets drawn into the combustion chamber? Engine vacuum is highest when decelerating.

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I’m betting this is leaking/worn valve guide seals, a known weak spot on Toyota V6 engines. They leak on the downhill with the throttle closed, high engine vacuum. Not big money to fix. Or just live with it.

Any short period of smoke when starting first thing in the morning?

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I’d step up the oil viscosty 5 to 10 points… 5W30 to 10W40, 5W20 to 10W30 and keep driving it and adding oil regularly. Buy a case and put it in the back. Check at every fuel fill up.

I’d also try something like Restore that supposedly fixes oil burning. It can’t hurt and it might help.

If your location doesn’t have emissions checks, I’d ignore the replacing the catalytic converter as well.

And I’d start saving for a newer car. This one is not worth dropping $10K into.