Oil burn on startup?

[A1218]

I have 192,300 miles on my 97 Pathy and I occasionally notice a little blue smoke after it’s parked for a little and I restart. No smoke at all while driving, only on the start and it’s not all the time either. Maybe a handful of times I’ve seen it in the past two years.

I changed my oil every 3,500 using high mileage synthetic and I check it often. It’s been changed at that interval for the life of the vehicle. If I ever have to tap up between changes and it’s never more than a half of a quart, I think its more from the slight oil leak near the bell housing of transmission. Don’t know if that’s a rear main seal leak or oil pan leak as that oil drips a few times as soon as engine is turned off.

Is this some detrimental or can I live with this?

[MisterH]

It's most likely that you have at least one or multiple valve stem seals that are worn out and allowing oil into the combustion chamber via the cylinder head. Oil that's pumped up into the cylinder head while the engine is running will leak down into the combustion chamber after you turn it off if the stem seals are gone. You can take a look at your spark plugs to determine which cylinders are burning oil. The good news is that you don't have to pull the engine to replace them.

[mdmellott]

Two typical causes of this are worn valve stem seals and guides, no longer stopping oil from seeping onto the backside of the valves, and worn oil seal rings on pistons, allowing oil to get past the gaps in the compression rings. There isn't much that can be easily done to remedy these, short of a tare down to replace stuff.

If it's a valve stem seal issue, using a non-synthetic oil instead will help since that has a much lower flow rate than the synthetic you are using does. If it's an oil ring issue, the non-synthetic could help there as well for the same reason but there is also a growing issue happening if the oil seal rings are worn. As excessive oil gets past the oil rings and squeezes past the compression rings, it fills the compression ring grooves of the piston and slowly builds up carbon, which will lead to failed compression as the rings eventually get seized up in the grooves.

Eight ounces (half a can) of Seafoam High Mileage motor treatment added to your crankcase, at a couple hundred miles before your next oil change, will do wonders to clean up a lot of built up yuck in your motor.

[A1218]

Thanks guys, I’ll have to take a look at the spark plugs. But like I said before I don’t see it occurring that often. Why is that so? If it’s an oil ring wouldn’t I be burning while driving also.

And on an old motor is it a safe option to use seafoam to clean it out without any damages occurring or causing other types of leaks to occur by damaging seals? I never used it before and I thought it wasn’t good to flush it out? How often is that done anyways?

[mdmellott]

Why is that so? If it’s an oil ring wouldn’t I be burning while driving also.

And on an old motor is it a safe option to use seafoam to clean it out without any damages occurring or causing other types of leaks to occur by damaging seals?

In either case, valve seals or oil rings, when the condition is not in a state of near total failure, oil may not readily pass through where it is not supposed to while the engine is running. If either case was severe, oil would be flowing where it should not, and burning while driving. In less severe worn conditions, temperature differences, between the areas where oil should and should not flow, separated by the seals and rings, will keep the oil from seeping into the cylinders, for the most part. When the engine is turned off, the combustion chamber area cools down and oil that is sitting in the piston ring grooves or on top of the valve retainers is drawn into the chamber. It's a physics sort of thing. When you start the engine, that small amount of oil is then burned and the smoke is pushed out through the exhaust.

I wouldn't use a motor flush product for cleaning the engine interior as a maintenance task but using an oil detergent product periodically is always good for the engine. CD-2 Oil Detergent was my go-to product for years and years but the company that made it is now out of business. It was a great product but I suppose big name competitors took their share of the oil additive market. Liqui Moly, Lucas, and even Seafoam are good alternatives. Although Seafoam would not be considered an oil detergent, and it is more aggressive than the likes of Liqui Moly and Lucas additives, it does have lubricants in it that help with the cleaning and freeing up sticky lifters, rings, and the like. I used it recently in my crankcase to free up a sticky or slow responding VVT issue. I was amazed how well it worked and it hasn't caused any seals to leak. Knock on wood.

[Mike W.]

Mine does use some oil and seems to be getting worse, but once in a while it will not send out a puff of smoke, but a full fledged smokescreen. But only once in a while. I fear the missing screw and damage it's done, and or a cat problem sucking in ceramic material but don't really know.

No help unfortunately, just a data point.

[A1218]

I'll monitor it for now, its very occasional and I dont really loose much oil to talk about in between changes. I will try that seafoam high mileage out in the oil and gas tank that Md mentioned earlier before the next oil change.

[AlanAZ]

The seal conditioners in a quality high-mileage oil can help a little.

This won't help with the start-up puff, but I'm an advocate of BG EPR (formerly known as 109.) Restores compression, smooths out and quiets the idle (cleaning sludge from oil passages -- I was beginning to think my QX4 needed new engine mounts before the first treatment), reduces oil consumption, and improves mpg. A LX470 owner reported a 2 mpg improvement. In an over-abundance of caution, I change the oil filter a 2nd time 500 miles after a treatment in case the first got sludged, particularly with a first treatment, and I don't do back-to-backs.