Question: I own a 2011 Toyota Camry with 116,000 miles. Is there ever a need to replace or service the timing chain due to routine maintenance? The salesperson who sold me the car said it should last the life of the car. — G.K., Naperville, Ill.

Answer: Timing chains do last the life of the car. Timing belts, on the other hand, require routine replacement — usually around 100,000 miles. If the vehicle has an “interference engine,” one where the valves and pistons crash into each other if valve timing is lost, that engine becomes a boat anchor. Check your vehicle’s owner’s manual.

Question: We just purchased a 2022 Mercedes-benz GLC 300 SUV. In receiving the post-purchase talk with the service manager, he indicated the need to run premium gas (91 octane) in the vehicle. I told him many gas stations carry premium (93 octane) or plus (89 octane). Are there any issues with alternating both premium and regular to get an average of 91 octane? — J.Z., Allentown, Pa.

Answer: I advise against switching fuels back and forth. But I am OK with mixing them together at the pump. Determine the capacity of your tank and fill halfway with each octane gas. Of course, it’s unlikely that you will have a dry tank so you have to do the math. You might try watching the fuel gauge on the dash and switch to the other octane gas at the midpoint. Of course, you will have to finish one sale and initiate another.

Question: At a recent service inspection, I was advised that the rear frame in my 2011 Ford Escape was severely rusted. It may eventually be unsafe to drive. Who would be able to do a repair? Is there some warranty or recall provision that I can use? I am looking for a way to move forward. — B.H., Chicago

Answer: Ford has had several issues with subframe rust and issued recalls for 2001-04 Escapes. I am not aware of a recall for the 2011 model year. You can contact a Ford dealer and inquire or you may choose to log onto the NHTSA website ( nhtsa.gov/ recalls) and enter your car’s VIN. A welding shop may be able to fix the problem.

Question: I have a Subaru Forester that I absolutely love and don’t want to part with unless I have to. I moved from Connecticut to Michigan three years ago. It currently has 113,000 miles and I want more. The check engine light has come on several times in those three years and has been fixed with minor repairs like the gas cap. However, the light came on a few months ago and my mechanic said it had to do with emissions. He said if the light is flashing, it means “fatal.” Yesterday I drove it for about 15 minutes. No light. I’d like to believe it’s a miracle and it fixed itself, but I don’t. — N.M., Brooklyn, Mich.

Answer: The check engine light always has something to do with emissions. Of course, various components in various systems (spark plugs, gas caps or even a thermostat for instance) can go bad and cause emissions to go up and trigger the light. If the light goes off by itself, the problem was intermittent. If the problem does not reappear after 50 ignition key cycles, the light will stay off. The problem has gone away. Professional automobile technicians can examine everything using a sophisticated scanner that plugs into the on-board data link connector. Getting reliable information is worthwhile. The full report may help you decide whether to keep or sell.