Motormouth: Gas pumps are tested for accuracy

Q: I buy my gas at a Giant food store because I receive gas discount points. I suspect that Giant's gas pumps dispense less gas than is shown on the pump. When I pump, a noise sounds like air is getting into the gas. When I am near empty, I end up dispensing over 19 gallons at Giant but only 18 gallons elsewhere. Do you think the Giant pump is reading more than the amount of gas being pumped? What can I do about this?

E.G., Philadelphia

A: States, including Pennsylvania, have bureaus of Weights and Measures. Inspectors make their rounds annually checking not only fuel dispensers, but scales and more. They use highly accurate field standards and equipment to inspect and test gas pumps. After pumps are inspected, they receive a sticker attesting to their accuracy and showing the date of inspection. If you don't see that sticker, contact the state authorities. Incidentally, gas discount promotions often limit the purchase to 20 gallons.

Q: In your recent Q&A, you answered a question about a broken/missing metal flap in the gas filler pipe. You said it was to prevent siphoning. My memory may be questionable at times, but didn't that flap get put in there to prevent a leaded gas filler (nozzle) from being used to fill a car with a catalytic converter and unleaded fuel engine? The diameter of the unleaded fillers was made smaller than the leaded fillers so only unleaded fillers could push open the flap.

B.B., Shoreview

A: You are right — partially. In the early days of low-lead and unleaded gasoline, a restrictor was placed inside the car's filler neck. This did indeed prevent the nozzle of the leaded gas hose from being inserted. The flap was added later to prevent siphoning.

Q: The MIL light on the dash of my Dodge Grand Caravan came on. I took it to the dealer. They scanned the computer for faults and said the thermostat was the problem. I got a second opinion from another dealer and was told the fault read, "thermostat rationality." The light has now gone out after eight days. Should I have it repaired? I don't want to break down.

A: The MIL (malfunction indicator lamp) will go out if the problem is no longer present. On some 3.5-liter engines, the thermostat may come loose and partially fall into the engine block. That allows coolant to sneak by the thermostat. Installing a shim usually corrects the problem. Otherwise, a replacement thermostat housing, with a built-in shim, is required.

Q: I have a new 2018 Audi SQ5. My remote gate opener does not work. Both garage door openers work fine. What can I do?

T.D., Oakbrook, Ill.

A: Most remote gate openers operate on the old dip switch technology. Modern automotive technology is quite different and does not have DIP switches. If your old remote opens the gate, but your onboard buttons do not, either upgrade the gate opener or keep your old remote handy.