Q: I recently purchased a 2020 Chevy Colorado pickup. This is the first vehicle I have owned that came with no gas filler cap. I am concerned about moisture getting in the fuel tank when it rains. The owner's manual does not cover this concern. Do I need to worry about this?

A: Don't give it another thought. The filler has a positive seal, which it is required to have in order to prevent fuel vapors from escaping and causing air pollution. Frankly, we see more check engine lights triggered by bad gas caps than the capless systems.

Cost of a good deed

Q: You told a writer wondering about the cost of running errands for an elderly neighbor that the IRS standard mileage rate is 57.5 cents per mile. That's correct for business purposes, but the IRS allows only a 14 cents-per-mile deduction when volunteering to drive for a charity.

A: That's right. However, the writer was not asking for tax advice, just a way to calculate the cost of operating a vehicle. When we perform charity work, part of the charity is the costs we absorb.

Oven cleaner to the rescue

Q: I've been in the auto repair business for 45 years. In regards to your answer to traffic paint on wheel wells and fenders, a good tip for your readers would be to use oven cleaner.

A: Good idea. I once draped my rain gear over my motorcycle. It contacted the hot exhaust pipes and melted. A buddy suggested warming the bike and applying oven cleaner. Nothing I had tried before that had worked.

Spring fling

Q: During our Minnesota winters, I see a lot of cars parked with the windshield wipers locked in a position up off the windshields. Does this stretch the springs we rely on to hold the wipers against the windshield?

A: It has no real effect on the springs.

Hands-on advice

Q: We have a 2016 Mercedes S Class 550. On a long driving trip and my partner is driving, a light showing a pair of red hands appears on the dashboard. When I am driving, it does not happen. It's a warning of some sort, but nothing is mentioned in the manual. Can you help me out?

A: It's a "hold the steering wheel" warning.

One side fits all

Q: I have always rotated tires every 7,000 miles or so. My 2016 Cadillac ATS has directional, run-flat tires. The owner's manual specifically states that "directional tires should not be rotated." I never heard of this. Can you shed some light on this please?

A: Directional tires must remain on the side of the car on which they were originally installed. There are arrows on the sidewalls indicating the direction of wheel rotation.

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 motormouth.tribune@gmail.com.