Q: I have a 2002 Lexus ES300 with 185,000 miles on it. Some time ago, the ABS and brake light came on simultaneously. I took it to my local shop who diagnosed a faulty ABS sensor. They said that I did not really need to replace it since it would cost close to the value of the car and that, even with a faulty ABS system, it would revert to normal braking and I'd just need to be more careful about braking in inclement conditions. I have not noticed any problems with braking. I don't really want such an expense for an old car. Should I be concerned?

— S.M., Plymouth, Minn.

A: The anti-lock brake system provides significant safety, especially in slippery conditions. Under normal conditions, however, the ABS does not kick in. The vehicle stops with its normal brake system. So, your shop is correct, but keep their admonition in mind as your drive. Since the problem is intermittent, I suspect a bad sensor or electrical connector, and repair may be less than the value of your car.

Q: I am a boomer who loves reading your column every week. My older brother, another Bob, is also very good with all mechanical things. When I ask him how he learned so much, he simply says, "poverty" with a chuckle. I wonder how you learned so much about cars. It amazes me how you know the facts and answers to the strange questions. I drive a 2019 Subaru Outback and I think we got a great vehicle, and I only have to ask my son or daughter-in-law how to reset the clock for daylight saving time. Thank you for all I have learned from your column.

— C.T., Lake Forest, Ill.

A: Poverty is an inspirational teacher. I too lacked money, which forced me to maintain and repair my cars. I learned from many mentors and lots of factory training when I worked as a professional mechanic. I still read trade publications (I used to be the editor of one) targeted to professional technicians to keep up to date. When I am stumped by a strange question, I turn to my cadre of techs and aftermarket suppliers for help. Yeah, I check out the internet. Some of the information is helpful, but there is also a lot of poor advice that we must take care not to follow. Thanks for the kind words.

Q: How is it that pure antifreeze freezes at about zero degrees F and water freezes at 32 degrees F, yet when a 50/50 mixture of each, the mixture freezes around 36 degrees below zero. Understood that is for sea level.

— D.O., Bechtelsville, Pa.

A: We had to turn to the folks at Prestone to explain this one. The simplest way to think about it is that water and antifreeze (ethylene glycol) are both pure but when they are mixed, they react with one another to form a new molecule. On their own, water and ethylene glycol react one way but when they are mixed and become an ethylene glycol-water hydrate molecule, which has whole different set of properties and performance. Prestone said that the cold freeze performance and hot boiling performance max out at about a 70/30 mixture. Once you get beyond that, the performance starts going back more toward straight ethylene glycol rather than the new molecule.

Bob Weber is a writer and mechanic who became an ASE-certified Master Automobile Technician in 1976. He maintains this status by seeking certification every five years. Weber's work appears in professional trade magazines and other consumer publications. His writing also appears in automotive trade publications, Consumer Guide and Consumers Digest.