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Q: I have 2001 Lexus RX300 with only 46,000 miles. I bought it new and have kept it in mint condition. In recent years, I have put on only 1,000 miles per year and have switched to a once-a-year oil change. I know the "book" says you should change oil every six months, but I also have read that you can go much longer than a year depending on how you use the car and mileage. In your opinion, is once a year OK?

A: Oil change intervals have changed from 3,000 miles/3 months, then to 7,500 miles/12 months, and now to whenever the warning appears on the instrument panel. But if your 1,000 annual miles are due to short trips (which seems likely), I suggest you change the oil and filter at least once a year. Short hops do not allow the engine and oil to get hot enough to cook off any moisture that may have condensed in the crankcase.

Inflator rater

Q: Can you recommend a heavy-duty portable tire inflator? I need one that is strong enough to add air to my Titan pickup tires. The one I have is OK for the smaller tires on my car, but it struggles with the Titan tires.

A: I have not used a 12-volt compressor in the 100-psi range, but there are plenty out there. Many Titan pickups also have power inverters that provide 120 volts AC power. More power to you.

Fuel problems

Q: I was buying gas at a top-tier gas station when a generic tanker truck pulled in and started filling up the storage tanks. Years ago, tanker trucks that went to gas stations had the brand on the truck (Shell, Sunoco, BP, etc.); now all I see is generic. I asked the tanker driver, and he said all gas at the tanker farms comes out of the same storage tank, hence, it's all the same. Who puts in the detergent additives?

A: Gasoline is a commodity shipped from major refineries to tank farms. Before that gas is shipped to the retail stations, it is blended by the marketers. Top-tier fuel has a better detergent package than the EPA requires and is worth seeking. A few companies have their own dedicated fleets of tanker trucks, while many contract with various carriers.

Hot stuff

Q: Before a recent trip, I checked my tire pressure, and all four were at the recommended cold tire pressure of 35 psi. About 90 minutes into the trip (it was a hot day), the tire pressure light on the dashboard lit up. All four tire pressures were at 37 psi. Is this a matter of concern? They are original tires (only 39,000 miles on them).

A: Tires flex as you drive, and flexing causes friction and heat. The air pressure then goes up. Warm tire pressures vary. You may ignore common increases in pressure.

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