Question: I drive a 2001 Lexus LS430 with 58,567 miles. The car manual says I should use gasoline with an octane of 96 or higher. I cannot find an octane that high. Any suggestions?

— J.S., Fort Lauderdale, Fla.

Answer: The LS430 owner’s manual states: “Only unleaded, 91 octane (research octane number 96) or higher.” In the United States, the octane number displayed on the pump is not the same as the research octane number. Instead, pump octane is the average number derived from the research octane number plus the motor octane number divided by two (R+M/2, which is also called the anti-knock index). Outside the USA, Canada and a few other countries, RON (research octane number) is the standard used.

Q: Toyota was one of the first to adopt daytime running lights to all their cars. But I’m wondering, how come I see more and more newer Toyota cars without DRLs? What’s happening?

— A.K., Skokie, Ill.

A: Toyota is not the only carmaker that provides the option of turning off the DRLs, but the company does make it easy enough to unintentionally turn them off. For example, the 2016 Corolla comes with three different switch types, two of which offer a “DRL OFF” option. When you turn the end of the lever to the “DRL OFF” position, your daytime running lights will be off. By the way, if you choose this setting, the automatic “headlight on” feature also will quit working.

Q: Thank you for answering the question about the price difference between grades of gasoline. Please go further and address the regional differences. In Chicago, it’s often $1.00, twice as much as the $0.50 average nationwide between economy and premium.

— D.B., Chicago

A: When we checked the AAA gas price website (www.gasprices.aaa.com) on July 17, 2017 (when we were writing this column), the average prices in Illinois were $2.295 for regular, $2.656 for midgrade and $3.038 for premium gas. The prices in major cities are often higher than the state average due to the requirement for lower emissions-producing fuels. We have a hunch that market factors may contribute to higher prices in areas where dealers have higher operating expenses. By the way, expect premium prices to keep going up as demand increases for turbocharged engines.

— 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. Send questions along with name and town to Motormouth, Rides, Chicago Tribune, 435 N. Michigan Ave., Fifth Floor, Chicago IL 60611 or motormouth.trib@verizon.net.