Consumer Reports sees oil vanish from some test cars

Lately it seems an undue number of test cars at our track have been going through motor oil. We can remember years when we barely had to add oil to any test car between service visits. Something has changed.

We think most consumers don't want to pop the hood and add oil between oil changes. Those days are gone, in theory. But now we've had several cars that need regular infusions.

Our latest car drinking oil is our $105,000 2012 Porsche Panamera, which is consuming a quart of 0W-40 motor oil about every 2,000 miles. With a 10,000 mile oil change interval, that's five quarts of synthetic oil (at about $8 per) in between oil changes. Several of our drivers got caught out by low oil warning lights and went searching for this obscure lubricant at night while out on the town. And trust us, not every corner convenience store carries 0W-40-weight motor oil. When we talked to Porsche about this, they said this usage was within spec. But we think somebody who bought a $100,000 car probably expects better.

And the Porsche is not the most egregious example. This writer bought the Consumer Reports 2008 Volkswagen Eos test car and kept it for five years. The whole time, it used a quart of equally expensive 0W-20 motor oil every 1,200 miles (accumulating black soot on the rear bumper above the tailpipe the whole way). After several trips back to the local Volkswagen dealer to document the problem, I was told that the VW spec for this engine was, exactly a quart every 1,200 miles. Since I couldn't prove it was using more than that, VW wouldn't help. That car also specified a 10,000 mile oil-change interval, for regular maintenance. By then, all the oil in the sump had been replaced twice.

Learn how to check your engine oil and other maintenance advice in our special section.

This problem has plagued other cars, too. In 2006, Mercedes replaced the V6 engine in one of our test cars under warranty after we finished testing them, because of excessive consumption of 0W-40 oil.

Even Japanese cars known for their reliability have lately been burning oil. When I took our 2012 Subaru Impreza to Boston for a weekend, it dropped down a quart on my way back, prompting a late-night search for more 0W-20 weight oil.

Auto engineers have told me they see no correlation between today's lightweight "0W-" motor oils, designed to reduce friction and save gas, and excessive oil consumption. But in our admittedly anecdotal experience, both the prevalence of such lightweight oils and the propensity of more engines to consume oil seem to be moving in tandem. And our test cars that have had this problem have all used such lightweight synthetic oils.

Has anybody else seen a correlation? Had a problem with a relatively new car consuming excessive amounts of oil? Do you think "a quart every 1,200 miles" is normal and/or acceptable for a modern car? Please let us know in the comments, below.

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—Eric Evarts

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