Motormouth: Fuel sources on Top Tier list are worth seeking out

Q: Less than a year ago, I purchased a 2016 Infiniti Q70 with a direct fuel injection engine. I have ever since gone out of my way to use gasoline that is Top Tier rated, with the belief that such fuel will help prevent my fuel system from needing the routine servicing often promoted by auto dealer servicing departments. I was also influenced by a joint study by AAA and Consumer Reports that found Top Tier gasoline is worth the extra cost. What is your judgment on this issue?

A. M., Huntley, Ill.

A: Your hunch is right on. We have advocated Top Tier fuels since the creation of the standards over a decade ago. To see a full list of Top Tier gasoline marketers go to toptiergas.com/licensedbrands.

Q: I have a 2011 Chevrolet Colorado pickup. It has no security system or any other aftermarket electronics. Periodically when starting, I turn the key and although all the system lights illuminate, the engine will not turn over. The starter does not click and there is no other sound. Repeated efforts do nothing and only after it sits for about 10 minutes will it crank. This never happens on the initial start, only after the vehicle has been driven and the engine is hot. The battery is new. The dealer was unable to troubleshoot the problem because there was no computer code and they advised there is no applicable service bulletin.

T.H., Minneapolis

A: Your truck does have a security system, GM's Passlock. Your ignition key has a built-in resistor whose value is read by the body control module that allows starting the engine. To deter theft, the system will prevent starting for 10 minutes if the wrong key is used. Try your spare key. If the problem persists, the lock cylinder or a poor wiring connection or module may be the culprit.

Q: At 30 to 40 mph, my 2013 RAV4 vibrates. The dealer said it was the tires. With new tires and $900 later, I have the same vibration. Any thoughts?

A: There are myriad causes of vibrations including motor mounts, universal joints, engine cradle misalignment, rim (wheel) run-out and more. But we have to ask what kind of wheel balancer the dealer used and how carefully the weights were placed on the wheel: Was it capable of testing road force? Hunter Engineering makes perhaps the best with its GSP9700 balancer.

Q: I have a 2005 Buick LeSabre that sat in the garage for two years and I now drive. One morning the needle on the temperature gauge went a little past center, which is not normal. My mechanic said the problem was with the temperature gauge; he flushed the cooling system and it worked fine for a while. Then the needle went into the red. My wife is afraid to ride in this car.

T.D., Easton, Pa.

A: Although the gauge could be the culprit, we would try a new temperature sensor, which would cost a lot less money. We would also check the coolant temperature using an infrared, no-contact thermometer, paying particular attention to the radiator for areas of varying temperature which would indicate a restriction.