How often should I change oil on a car I rarely drive?

Q. I have about 1,000 miles on my 2005 Corvette since its last oil change two years ago. Do I need to get an oil change for the upcoming season’s car show and driving season? Also, we flushed the coolant and added fresh Dex-Cool antifreeze three years ago. Is that okay and should it be changed? 

A. I am a big believer in yearly oil changes even when a car only goes limited miles. Oil does not deteriorate by sitting, but short drives can contaminate oil. One alternative to low mileage oil changes is periodic oil analysis. Having a lab check an oil sample will tell you about the overall oil quality and contamination. As for the coolant, generally Dex-Cool is a coolant with a lifespan of five years.

Q. A vague haze seems to accumulate on the inside of our windshield. On days of temperature change and humidity, the inside windshield fogs. Fortunately, the defroster clears it efficiently. We are wondering why this happens. A few wipes with SprayWay glass cleaner will clean it off until the next episode. This recent time that I changed my cabin filter I was advised that many times the filter is changed and sprayed with a scent. I did not scent my filter. Might this spray be the cause? 

A. As you pointed out, it is the temperature change that causes the issue. SprayWay and some people say shaving cream works in the car just like it does to some extent on a bathroom mirror. It helps prevent the moisture/steam build up or adhesion of moisture. Opening the windows slightly to adjust the temperature can help, as well as adjustment of the heater/air conditioner temperature. But realistically it is just like fog on the road – moisture and temperature are the culprits. As for the filter, no, I do not think that is the issue. 

Q. I have read about things exploding inside cars in hot weather, such as spray paint, hand sanitizer, and even soda cans. Is this real or another urban myth? Also, how hot can it get in a car on a 90 degree day? 

A. One 90-degree day I left a thermometer in a car just to see how hot it would get. At the peak heat of the day, about 2:30, the car reached about 135 degrees. The TV show MythBusters, busted the soda can myth stating it took over 300 degrees for the can to burst. Most spray paint cans warn against storing at over 120 degrees. Hand sanitizer contains alcohol and is flammable, but will take temperatures higher than the interior of a car on a hot day to spontaneously combust. My advice is that combustible materials should never be stored in a vehicle. And most importantly, never leave a child or pet in a hot car. Heatstroke can happen in just a few minutes on a very hot day. 

Q. At about 27,000 miles my wife was told by the dealer that her 2018 Subaru Legacy required rear brakes at a cost of about $700. I always thought that the front brakes wore out before the rear ones. I also thought that there is a law that requires the installer to return the old parts to the owner if requested. 

A. Generally, you are correct, the front brakes do about 70 percent of the braking which is why they wear out faster. Still, some cars will wear out rear brakes quicker than others. Some Honda Accords from 10 years ago were wearing out rear brakes in as little as 20,000 miles. Regarding the returning of old parts, in Massachusetts, where I live, you have the right to get your old parts back if you request them. If the repair shop must return the old parts to the parts manufacturer or another entity under a warranty arrangement or core charge, then you have the right to inspect the parts before they are returned. 

Q. I have been having this issue with my car lately and no one has a clear answer for it. One of my neighbors told me to reach out to you about this issue. The horn on my 2018 Honda CR-V LX AWD sounds after using AC and turning off the engine. My Honda dealer said there is a hole in the radiator, and it is causing this sound, but I do not see any coolant leaking, or the engine overheating. The coolant level is stable. The AC works fine. The dealer claims that the AC compressor is fine, and wants to charge me $1,430 for replacing the radiator, which I feel would not resolve the issue. Please help me find a solution.

A. I agree that it is not the radiator, for all the issues you stated. I believe it is the air conditioner expansion valve that is causing the noise. The part is $100 and about 1.5 hours to replace it, plus a refrigerant recovery and recharge. Still, it should be checked just to make sure it is not some other odd part failure. In case it comes up, I believe the AC compressor on that vehicle has a warranty extension from 3 years to 10 years (no mileage limitations) due to premature failure. 

John Paul is AAA Northeast’s Car Doctor. He has over 40 years of experience in the automotive business and is an ASE-certified master technician. E-mail your Car Doctor question to [email protected]. Listen to the Car Doctor podcast at johnfpaul.podbean.com.