Excessive oil consumption isn't normal

 Cars under warranty shouldn't burn oil. And most don't.

But Consumer Reports' 2014 Annual Auto Survey found that several auto manufacturers are building engines—available in a number of widely sold models—that require frequently topping off the oil reservoir between recommended oil changes. That's a worry and cost that a new-car owner shouldn't have.

The oil-change industry has long prescribed changing your oil every 3,000 miles. In recent years, most automakers have stretched that to 7,500 or even 10,000 miles because refinements in engine manufacturing and oil technology purportedly allow engine oil to last longer.

For some automakers, though, that appears to be an optimistic claim. In our survey of owners of about 1 million vehicles stretching back 10 years, we found that for certain models, significant numbers of consumers have to add a quart of oil to their engines as frequently as every month.

It's normal for cars to burn a little oil as they age toward 100,000 miles and beyond. But Consumer Reports believes that for an almost new car to burn that excessive amount of oil is unacceptable. 

Does your car suffer from excessive oil consumption? Tell us about it by leaving a comment below.

We focused on 498,900 vehicles from the 2010 to 2014 model years, many of which are still under their powertrain warranty. Several engines emerged as the main offenders: Audi's 2.0-liter turbocharged four-cylinder and 3.0-liter V6, BMW's 4.8-liter V8 and twin-­turbocharged 4.4-liter V8, and to a lesser extent Subaru's 3.6-liter six-cylinder and 2.0- and 2.5-liter four-cylinders.

Those engines are in models such as the Audi A3, Audi A4, Audi A5, Audi A6, and Audi Q5; BMW 5, BMW 6, and BMW 7 series, and BMW X5; and Subaru Forester, Subaru Impreza, Subaru Legacy, and Subaru Outback.

The worst case showed that, overall, owners of BMW 5 Series vehicles with V8 engines were 27 times as likely to suffer excessive oil consumption as owners of an average vehicle.

Already, some manufacturers are facing off against angry consumers who are finding that carmakers aren't backing up their products.

Audi, BMW, and Subaru stick firmly to the statement that oil consumption is a normal part of a car's operation. Subaru considers a quart burned every 1,000 to 1,200 miles to be acceptable. Certain Audi and BMW cars' standards state that a quart burned every 600 to 700 miles is reasonable.

If a driver has to add a quart of oil once per month, that can mean adding up to 7 to 9 quarts of oil between oil changes. Those costs due to excessive oil consumption can add up because automakers more frequently require synthetic oils that can cost upwards of $9 per quart—in addition to the expense of the routine oil changes.

Consumer Reports data does not show a direct connection between increased oil consumption and other engine problems. But our survey data concerning 10 model years shows that if a car burns oil early in its life, it will burn even more as it ages. In tracking oil consumption by model year, engine families show increased consumption with each successive year on the road.

Having to add oil isn't a problem that will necessarily strand you by the side of the road if you are vigilant about monitoring your oil levels. But we think it's a serious problem that automakers should address.

Not all engines suffer from this problem. In fact, our data shows that owners of 98 percent of 2010 to 2014 cars did not have to add oil between changes. But the cars that do burn oil do so furiously. Even if only 2 percent of vehicles sold since 2010 have this problem, that still represents about 1.5 million vehicles on the road.

Consumer Reports believes that any engine that burns oil between changes should be repaired under the powertrain warranty. But automakers often shield themselves in the fine print of their owners' manuals.

In some cases, when confronted by a customer complaint, the manufacturer has authorized a dealer to repair, rebuild, or replace the engine under warranty. In other cases, though, some manufacturers are defending the oil consumption as falling within the car's technical specifications—or they blame the car's owner for his or her driving habits.

Shelly Shugars, a training director from Tivoli, N.Y., bought a new 2012 Subaru Impreza Sport hatchback and had her first oil change done on schedule when it hit its first 3,000 miles. But since that oil change, she says she has been adding a quart of oil every 800 to 1,000 miles. Shugars says her Subaru dealer told her that her car's oil consumption is normal, although the automaker offered her $500 for her trouble. Rebuilding the engine to fix the problem would cost far more.

Shugars is far from alone. Subaru and Audi are in the midst of class-action lawsuits regarding the problem.

Subaru's director of corporate commu-­nications, Michael McHale, said in an e-mailed statement, "The rate of consumption can be affected by such factors as transmission type, driving style, terrain, and temperature."

For consumers who complain about excessive oil consumption, Subaru has authorized its dealers to perform oil-­consumption tests to determine whether the vehicle is performing outside of manufacturer specifications. Subaru began modifying its engines on certain models starting in 2010 but took until 2014 to modify others.

Meanwhile, a settlement to a class-action lawsuit against Audi would extend the power­train warranty on its 2009 to 2011 model-year CAEB 2.0-liter turbo engines to eight years or 80,000 miles. Audi declined to comment on the litigation or oil-­consumption problems in general. Our data shows that newer Audi 2.0-liter turbos and V6 engines are also burning oil.

In a recent technical service bulletin, Audi recommended that "the customer always have a spare quart of engine oil in case the engine oil needs topping off while on the road."

BMW outlines such consumption as part of its manufacturer specifications. You can even purchase a traveling case for oil, to affix in the car's trunk.

"Oil consumption is normal on all engines," BMW spokesman Hector Arellano-Belloc said in an e-mailed statement. "BMW vehicles have long intervals between oil changes (10,000 miles). BMW engines (excluding the BMW M) may consume up to one quart of engine oil per 750 miles under certain driving conditions." He added that BMW's M performance models may consume even more oil than that.

Other manufacturers that have shown instances of oil consumption are taking corrective action.

Honda recently issued a warranty extension to eight years or 125,000 miles for 2008 to 2011 Accord and 2010 to 2011 CR-V four-cylinder engines. Honda said it had found that sticking piston rings could lead to higher oil consumption if the engine is revved hard when cold, when combined with prolonged usage of low-quality gasoline.

And following the filing of a class-action lawsuit in California regarding its four-­cylinder 2AZ-FE engines sold in some 2007 to 2011 models, Toyota amended its powertrain warranty on those engines to 10 years or 150,000 miles. A Toyota representative said, "This program provides complete relief to owners who are currently affected, as well as those who have previously paid for repairs."

Automakers are facing a dilemma: They want to reduce ownership costs and the ecological impact of their cars. Used engine oil can pose an hazard if not properly discarded, and internal combustion engines rely on routine changes. But wait too long to change your oil and it can foul—turning to sludge and damaging your engine.

Some consumers we followed up with told us they would not have bought their oil-burning cars had they known they would be checking their oil so often. A recent CR national survey of 542 American owners of a 2000 to 2016 model-year vehicle showed that 39 percent either never check their oil or only have it checked when taken in for service.

If consumers are being denied repairs and rebuilds on engines that consume too much oil, those cars could end up unloaded onto used-car lots by folks sick of adding oil. That just passes the problem on to the next owner.

If a car does consume oil under warranty, Consumer Reports believes the automaker should cover the repair costs for current owners and pay to top off the oil in between changes—and not just improve the engine's design for future buyers.

Burning up

The chart shows the percentages of surveyed vehicles that needed at least a quart of oil added between oil changes, sorted by model year. The chart does not include vehicles that leaked oil.

According to data from Consumer Reports' 2014 Annual Auto Survey of owners of 498,900 vehicles from 2010 to 2014 model years, these 30 models have much higher rates of oil consumption overall than the average for their model years.

If your car requires frequent topping off of its oil due to excessive oil consumption, you might have recourse from the automaker.

Take your car to your dealer, along with receipts for oil changes and oil purchased between oil-change intervals. Ask whether your car is eligible for repairs under any customer-satisfaction campaign or technical service bulletin.

Even then, the dealer may want to conduct an oil-consumption test before offering to perform repairs under warranty.

The test measures how much oil you consume over several weeks of driving. If your car's oil consumption exceeds the manufacturer specifications and it's still under its original powertrain warranty, Consumer Reports believes the dealer should repair or replace the engine free of charge. Some extended warranties will cover the problem. However, if your car is consuming oil, but at a rate less than the manufacturer guidelines state is excessive, you could be in for a legal battle.

If that is so, you may want to consult an attorney regarding lemon-law statutes. Also check to see whether your car is a part of an excessive oil consumption class-action suit already in progress.