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Q: A friend just bought a 2002 Corvette. It’s a nice car, but he neglected to check out the lug nuts. Each wheel has a locking lug nut. There is no key, and the previous owner is not answering his calls. Any idea on how to get them off without wrecking them?

A: Yes to the first part — there are several ways to remove the locking nuts, and professional technicians know how to do it. But, no, it can’t be done without damaging the lug nuts beyond repair, so your friend will have to buy a new set of locking nuts that will include a key. The other option is to get standard lug nuts.

Jake brakes, part 1

Q: Regarding recent comments about jake brakes: They are designed to slow a semi on a down grade. There is no reason, other than to save regular brake linings, for their use if there is no danger of the vehicle over-revving and the driver losing control. The use of jake breaks on flat terrain is the sign of a lazy, cheap, non-maintenance-focused driver. Jake brakes are remarkable safety accessories when used as designed.

A: I have no argument with the last sentence. But in residential areas, they are also a source of noise pollution. Here’s another reader’s thoughts on the matter.

Part 2

Q: A muffler has been developed to quiet jake brakes. But many truckers are not interested. They enjoy the engine brake noise much like Harley riders like their unique sound.

A: I hear you — and the trucks.

Don’t knock it

Q: I drive a 2017 Acura MDX. The owner’s manual specifies that 91 octane fuel is “recommended.” The sales staff told me that mid-grade (89 octane) or even regular grade (87 octane) is acceptable. I’ve used mid-grade for two years, and the engine and performance is good. Can the engine adjust to fuel that is lower than the recommended grade?

A: With a spirited driver, engine knock can occur, so the preferred fuel is one with a higher octane. Under less spirited driving, however, engine knock is less likely, so mid-grade or regular gas is fine — which sounds like the situation in your case. Continued engine knocking will cause damage, so a knock sensor on the engine reports the first signs of knock to the engine control module that then backs off the ignition timing until the knocking stops.

De-sludging a dirty deal

Q: We have a 2010 Toyota Highlander with 58,000 miles. On my last couple of visits to the dealer for routine maintenance, they have recommended an engine de-sludge. Is this something modern vehicles need, or are they just trying to get me for another $170?

A: If you’ve kept up on regular oil changes and other maintenance, they’re likely just cleaning out your wallet.

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.