A burning theory about burning through oil

Ray makes a good point in this week’s column about burning oil. There are a couple more facts that are not what was asked, but might be helpful to the fellow who wrote in.

At a quart of oil burned per 1000 miles, it is only a matter of time until the catalytic converter plugs up with ash.

There are several reasons why some cars chronically burn oil. My aunt’s Buick burned oil from the day she drove it off the lot. One reason is that manufacturers install weaker rings, reasoning that if the rings press against the cylinder walls with less force, there will be less friction, thus better gas mileage and less wear on rings and cylinder walls. This does not work, but they keep trying it. Weaker oil scraper rings are more prone to get stuck in their grooves after 100k miles or so, leading to excessive oil consumption.

Adding strong solvent to the oil and driving for a day or two before each oil change may help free up the rings. No guarantees, but it is a lot less work than the alternative.

What solvent and how much? Couldn’t the solvent be added through the fuel rail or carburetor for long enough to release the rings?

I personally use SeaFoam. I am not claiming it works miracles, but it seems to help slow down oil consumption in my 2004 BMW with 270k miles. I dump a pint can into the oil a day or two before each oil change. You can add cleaners into the top end, but since I am quite sure that my problem is weak oil scraper rings getting stuck in their grooves, I attack the problem from the oil side.

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Yes, this is part of the reason. These is more to it, though.

I used low tension oil rings in may race engines to make power. I did not care about oil consumption. And these engines were the only ones I have ever owned, new or used, that consumed any appreciable amount of oil.

A manufacturer cares about oil consumption because they must warranty the converters for 80K miles or 8 years by law. So it becomes a balancing act between CAFE mpgs and warranty cat replacements. It helps to have the proper pressure in the crankcase to keep the rings sealed, too.

The “free up the rings” treatments are not needed if you use the proper weight, good quality, oils and change per the manufacturer’s recommendation OR MORE OFTEN!

Too many people that have oil consumption problems create them by neglect. They THINK they are good with maintenance but buy white label oil and filters from quickie lube places thinking they are getting Dexos or VAG spec oils in their car.

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I’ve heard that theory, seems like common-sense, but haven’t seen much in the way of proof.

As far as the question posed, I had a co-worker who held to the same theory, that b/c his valve covers leaked one quart every month, no need to ever change the oil, just top it off once a month. He did change the filter from time to time.

I bought my '04 at 100k miles. I cannot speak to the maintenance or oil used prior to that, but it was burning a quart every 1000 miles when I bought it. It was burning a quart every 600 miles 30k miles later when both my catalytic converters plugged up. The car would go into limp mode and set a code for “MAF signal implausible” because it was reporting way to little air flow for the RPM and throttle opening. Obstructed exhaust was confirmed with vacuum readings and back pressure readings collected at the upstream oxygen sensor ports. Two California-compliant catalysts cost $1000 each. Only two vendors sell them and both charge the same.

Since I bought the car, I have used Mobil1 and Mann filters changed every 5000 miles. Oil consumption varies but at 270k miles, it is around a quart every 2k miles.

So it was using a quart every 600 miles but now it is 1 in 2000 miles? What did you do? The solvent add?

I bought an 89 Suburban wjth 96K on it. I switched to Mobil 1 and it used a quart in 500 miles or so, then 1000 miles. I did a change at 1500 miles and the consumption dropped to a quart in 1500, then to 2500 miles or so until I sold it. The Mobil 1 flushed all kinds of junk out.

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