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Q: The maintenance guide for my 2020 Subaru Forester suggests a brake fluid flush every 30,000 miles/24 months. I have never owned any vehicle that has recommended this with such frequency. The brake fluid in the reservoir is a honey gold color. Is flushing it really necessary?

A: Brake hydraulic system designs vary by manufacturer, and that factors into maintenance schedules. You might be able to extend your fluid flushes by testing the brake fluid for signs of corrosion that can lead to ABS problems. A test strip product such as Strip Dip will help you do that.

Seeing the light

Q: The 2015 Subaru Forester is designed so that the headlights remain on when the ignition key is in the off position. This can cause battery issues if driving with the headlights on during the day in rainy weather and then stopping at a rest stop for a break while remaining in the car. If you don't turn off the headlights or remove the key from the ignition, you could end up needing to jump the battery.

A: Consider it a feature, not a bug. When you select the automatic headlights on/off feature, the lights stay on long enough for you to safely walk away from the car. If you leave the key in the ignition, the headlights are a reminder that you forgot to remove the key.

Below the belt

Q: Our 2014 Kia Soul has 40,000 miles on it. I'm thinking it is getting close to time for replacing the serpentine belt. It looks fine, but I worry that our high Las Vegas temps might hasten its demise. What are your thoughts?

A: The serpentine belt doesn't usually snap suddenly. Small cracks in the grooved side are normal, but chunks are not. You can check the belt with a plastic tool that many parts stores give away.

Battery check

Q: I leave my key fob in my car overnight (the car is in a locked garage). Does doing that drain the key fob's battery?

A: The key fob battery won't drain prematurely, but leaving the fob inside some cars can keep the control modules awake. That might put a drain on the automobile's 12-volt battery.

Problem solved

Q: You recently responded to a reader who was looking for a locking gas cap for his 2001 BMW Z3 roadster. I have that same car and recently discovered that my gas cap was missing. My BMW dealer told me they don't make the part. I purchased a nonlocking gas cap from a supplier who says it's equal to the original one. I guess we'll see.

A: If the check engine light doesn't come on, the new cap is sealing properly.

Bob Weber is a writer, mechanic and ASE-certified Master Automobile Technician. His writing has appeared in automotive trade publications, Consumer Guide and Consumers Digest. Send automotive questions along with name and town to