Why does Camry need synthetic oil added every 250 miles?

The vehicle has used synthetic oil since it was new. Now, even after a complete oil change, I have been adding a quart of oil every 250 miles.

I found, after reading online, that the 2007 engine was the most problematic. Is there a remedy for this oil fiasco? My friend was never notified of any recalls. What is with that?

A: As good as some Toyota products are, some did indeed have problems.

Car Doctor:Is synthetic oil really worth the much higher price?

Repairing your problem requires replacing the pistons and piston rings and the connecting rods and bearings — essentially an engine rebuild. The original warranty was for five years or 60,000 miles, whichever came first.

Since the warranty is long expired, Toyota is not going to be of any help. At this point, you have a couple of choices: replace or rebuild the engine, or keep adding oil.

If this were my car, I would change to conventional oil. As much as I’m a fan of synthetic oil, at least topping off with conventional oil would be a little more cost effective.

Car Doctor:Corolla keeps stalling in heavy traffic and long idles

Q: I have a 2012 Chevrolet Colorado with a 2.9-liter engine that I have owned since it was almost new. The vehicle has almost 100,000 miles on it.

It has an intermittent vibration at idle with the truck in gear. In the summer, it is worse with the air conditioner on. This has been the case off and on the entire time I have owned it. Otherwise, it runs well. Any idea? Maybe motor mounts?

A: This engine has an inherent vibration which is a normal characteristic. Since the vibration has been there since day one, that rules out engine and transmission mounts.

I would want to closely inspect for a slight vacuum leak that could be causing a vibration. An indication would be abnormal fuel trim numbers, which can be checked with a scan tool.

On some models, I have seen a leaking intake manifold gasket. The leak may not be substantial enough to cause a misfire, but it could be enough to cause some shake and vibration.

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Q: I have a 2023 Ford F-150. The tire pressure fault light comes on and I can't read tire pressure electronically. I put on LT (light truck) tires that take 65 pounds of pressure. This was no problem with my 2020 F150 when I upgraded the tires to actual truck tires.

The tires that came with the truck took 38 pounds of pressure, which is listed on the door jam.

What needs to change to get the system to work properly? The dealer says I can't do anything to reset the light due to the new tires.

A: By changing to the light truck tires (keeping the same size 245/70R17) you have changed the load range from the standard to an extra capacity load range E. For the tires to carry the extra weight, they have a higher air pressure.

Car Doctor:How can I pinpoint the source of Honda's intermittent TPMS warnings?

Since Ford sells upgraded wheel and tire packages, I’m surprised the dealer can't change the TPMS air pressure limits.

The TPMS tool that I’m familiar with that allows both sensor relearn and programming is from Bartec. In addition to being able to reset the pressure limits, it allows the placard pressure to be changed.

It is possible that somehow, for the 2023 model, Ford has this feature locked down, but it's certainly worth investigating to get this safety system operating correctly.

Q: I have a 2002 GMC Yukon with 251,200 miles on it. The air conditioner and heater are not working properly. One independent mechanic told me the problem with the air conditioner was it needed a new condenser.

I am not comfortable with his diagnosis. I’m afraid there may be more involved in getting it to work correctly. The fan seems to work but that is all. The heater operates only as a defroster; no air comes out of the other vents.

What questions should I ask to find out who is giving me the truth and who is padding a repair job?

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A: The condenser is integral to the proper operation of the air conditioner but won't have any effect on the heater operation.

The issue is most likely related to the temperature blend door and duct motors. The system defaults to defroster operation for safety purposes.

Go into the repair shop and demonstrate what the heater and air conditioner are doing as well as what they are not doing. Once you and the technician are on the same page, ask for a complete estimate of the possible repairs.

John Paul is the AAA Northeast Car Doctor. He has more than 40 years of experience in the automobile industry and is an ASE-Certified Master Technician. Write to John Paul, The Car Doctor, at 110 Royal Little Drive, Providence, RI 02904. Or email [email protected] and put "Car Doctor" in the subject field. Follow him on Twitter @johnfpaul or on Facebook.