strong>Dear Doctor: Is there a way to adjust the sensor level for the automatic headlights on 2006 and 2007 Chevy vehicles? I have a 2007 Cobalt SS and a 2006 HHR. Both cars turn the headlights on at 10 a.m. in November with totally clear skies (unless I face into the sun). John
strong>Dear John: Vehicles equipped with the automatic headlight feature have a small electronic light sensor located on the top of the dash -- usually at the front of the dash by the windshield while others have the sensor mounted on the rearview mirror housing. The sensor is preset and there is no way to adjust the light sensitivity. Make sure the sensor is clean and free of anything that can cover it.
strong>Dear Doctor: I purchased a 1999 Nissan Altima from the original owner. It has 91,000 miles and has always been cared for. It has a factory alarm that works by locking and unlocking the doors and the lights flash, but the alarm horn does not sound. I have checked all the fuses and have tried toggling the fob on and off for the horn sound. I checked the horn itself and it works with a jumper wire directly to it. Any suggestions? Also, my Altima only gets about 22 mpg combined, which is very discouraging. Any suggestions for improving the mpg would greatly be appreciated. Bob
strong>Dear Bob: When it comes to the repair of any factory alarm system, the first thing a technician will need to do is go online to the Identifix site and obtain the wiring diagram of the system and then start the diagnosis. Regarding the combined fuel economy of only 22 mpg, I recommend you check a few items. First, check the tire pressure, and make sure there is no brake drag. Next, look at the maintenance items, including spark plugs and air filter. An often-overlooked area is the front oxygen sensor and thermostat. Both can get lazy without setting a fault code. I personally like the front oxygen sensor replaced at 75,000 miles. Switching to full-synthetic oil will add gas mileage. You also have to make sure the transmission is shifting into overdrive.
strong>Dear Doctor: For a 2006 Toyota Highlander with a six-cylinder engine is there a product that might stop a rear main seal slow leak? If so, does it go directly into the oil? What would you think is a fair price for repair of this issue? Would you also suggest having a shop, like Aamco, do this since I've been told it entails something involving the transmission? Ron
strong>Dear Ron: There are a few products on the market that claim to stop oil leaks. To date I have never seen one that works. You can switch over to a high-mileage oil, which may help. You also have to make sure the positive ventilation system is working. A partly blocked PCV system will cause extra pressure in the crank case system, as well as oil leaks. If you opt for the rear seal to be replaced, get a few price quotes, including the dealer's.
strong>Dear Doctor: I have a 2011 Chevy Cruze. I changed the oil for the first time at 2,000 miles in September before a taking trip between New York and Florida. At Thanksgiving, with the odometer at 6,000 miles, the car's computer says I still have 61 percent of oil-life capacity left. My garage says change the oil every 3,000 miles. Whose advice should I follow: the garage's or the car's computer? Steve
strong>Dear Steve: Great question and the answer is not easy. Auto manufacturers use a timer, driving habits and mileage to determine the remaining oil life. The time period varies between manufacturers. Some oil change intervals are on an annual basis, or 20,000 miles (that's right 20,000 miles), others are 8,000 to 12,000 miles. The long mileage intervals are with full-synthetic oil. For your car, and others that use regular petroleum-based oil, I am with the 3,000-mile or 3-month change interval philosophy. To some owners this seems like overkill, however, I still recommend it, especially if you live in the Snow Belt, drive on roads that are not flat, and drive in the city.
strong>Dear Doctor: We have a 2004 Ford Freestar minivan. The motor oil level drops 2 1/2 quarts within 2 weeks of normal driving, but there are no oil leaks or noticeable emissions releases. The van has a PCV valve with an electric connection to the PVC system. If this electronic PCV valve is not working properly, will this cause the engine to lose oil? Rob
strong>Dear Rob: Engines use oil for a reason. A blocked PCV system will cause high pressure in the crankcase and cause oil to blow into the entire engine, and yes, burn oil. Weak piston oil rings, worn valve guides, and in some cases, oil can be sucked into the engine from faulty intake gaskets and seals. I suggest you take your vehicle to the shop and let the technician check the engine to pinpoint where the oil is going.
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