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Can driving in Eco mode damage my engine?

John Paul, AAA Northeast's Car Doctor, answers a question from a reader who has heard rumors about problems related to Eco mode.

The Car Doctor answers a question from a reader who has heard rumors about problems related to Eco mode. Chevrolet

June 4, 2024

Q. I have a question for you about my 2019 Chevrolet Z06 Corvette. It has an electronic selector that allows the driver to change performance settings. It has been brought to my attention that after much use in Eco mode you can somehow damage the engine (something about the valve lifters). Do you know anything about this?

A. I find it unlikely. There are thousands of GM engines with displacement on demand, and yes, I suppose some very slight valve lifter wear could result when the engine is operating in four-cylinder rather than eight-cylinder mode. If this were a legitimate issue, then GM would simply reprogram the car’s computer to limit the Eco operation. I searched GM tech bulletins and didn’t find anything to indicate a problem. I did find a mention on a Corvette forum, but this was seemingly a rumor without any facts to back it up.

Q. I have a 2017 Genesis G80 with a 3.8-liter engine and all-wheel drive. About four years ago the car was dead as a doornail when I went to start it in the morning. My local Genesis dealer came to the house and picked up the car. They diagnosed the problem as a bad battery and replaced it for no charge. It is now three years later, and it happened again. I called the dealership and was informed they were no longer permitted to sell or service any Genesis branded vehicles. So now I’m stuck trying to find a facility with the expertise to work on the Genesis brand. I want the starting and charging system checked and the battery replaced if necessary. My question is twofold – can you recommend a qualified shop, and how can I be assured if the battery is disconnected that I won’t lose all the custom settings I have entered into the computers over the last few years. A Genesis qualified technician should know how to do this, so I am looking for a shop with this level of expertise.

A. Any good shop should be able to test the electrical system, and if the battery has failed, replace it using a memory saving device to save the various functions that you have programmed. The battery is a bit uncommon and not readily available, at least at AAA. The battery you are looking for is an AGM (not a standard lead acid) with the following specs: Model type AGM105 with 950 CCA rating and reserve capacity of 190 minutes. It is interesting that the dealer can’t service the car any longer. I can understand for warranty work, but if they were capable before they should be capable now. AAA does have the Approved Auto Repair network of shops. To find one in your area, go to aaa.com/repair.

Q. I currently own a 2017 Toyota Highlander with 87,000 miles. It has all-wheel-drive and a V-6 engine. Our previous vehicle, a Chevy Equinox, was enjoyable except that the 4-cylinder engine struggled on trips upstate, which is why we opted for the 6-cylinder Highlander. I have major reservations about owning a newer model Highlander which is available only in 2.4L 4-cylinder or 2.5L hybrid versions. Maintaining speed up some of the steep inclines while in cruise control in our previous Equinox models caused very uncomfortable surges in engine RPM. Are there better alternatives, or would the hybrid compensate somewhat?

A. You would need to drive one to decide, but let’s look at the facts. The 2017 V6 Engine makes 295 horsepower and 263-pound feet of torque. For 2024, the turbocharged four-cylinder engine makes 265 horsepower but an impressive 310-foot pounds of torque. It is the torque that realistically gives you more power that you need to make those steep hills. The hybrid version is more about fuel economy than power, with the numbers being good but lower than your current vehicle (243 horsepower and 263-pound feet of torque). As for alternatives, the Honda Pilot, Hyundai Palisade, or Kia Telluride (Kia and Hyundai numbers are closer horsepower/torque matches for your current Toyota) would be good choices.

Q. I have a question on my 2015 Buick with a 3.6 V6. I topped off my coolant reservoir the other day and I was surprised to see that I had to add about a half a gallon of coolant. I parked my car in the garage and there are no visible leaks. I got under the car the other day and looked and can’t seem to find where the leak is coming from. I’ve had similar issues with other GM cars that I have owned with Dex-Cool coolant that seemingly just evaporated. Any help you could offer would be appreciated.

A. Over the years I have seen some GM engines with a variety of internal coolant leaks, from the intake manifold to head gaskets. These are very slight leaks, and the coolant burns up during combustion. Not that many years ago, Cadillac would recommend the use of coolant sealer tablets (they looked like Alka Seltzer) to stop very minor leaks that were not visible to the naked eye. These tablets work well in all GM engines. It has been my experience that GM Dex-Cool coolant does seem to need a bit more attention than traditional coolant, and it is important to keep it full. At this point if the coolant is clean and protecting the engine, monitor the level and add as necessary.

John Paul is AAA Northeast’s Car Doctor. He has over 40 years of experience in the automotive business and is an ASE-certified master technician. E-mail your Car Doctor question to [email protected]. Listen to the Car Doctor podcast at johnfpaul.podbean.com.