GM specifies Dexos oil -- better use it

Dear Doctor: I just purchased a 2012 Chevy Traverse. The owner's manual calls for 5W/30W Dexos oil. I use Mobil 1 in all of my vehicles and I have 24 quarts of Mobil 1. Would it be OK to use this oil? The manual says if Dexos is not used I could void the warranty. -- Al

Dear Al: When it comes to any fluid to be used in any vehicle you must adhere to the manufacturer's specifications. In some cases, the use of synthetic fluids can void the warranty. I suggest you check with both GM and the synthetic oil maker and get in writing from both on the warranty issue.

Dear Doctor: I purchased a Chrysler 300. The car is loaded with all options and has only 7,000 miles. The aluminum wheels developed some noticeable corrosion by the center wheel caps under the clear coat finish. The dealer acknowledged there is a corrosion problem. They said the problem was caused from the soap I was using. If it were the soap, then wouldn't it have also damaged the clear coat finish? -- Kim

Dear Kim: You are not alone, as other owners of this model are having same corrosion wheel problem. The problem with the wheel corrosion is poor preparation and sealing of the aluminum surface before the clear coat was applied at the factory. If the problem were acid type soap, then the clear coat finish would be damaged and spotted, too. All the dealer has to do in order to remedy this situation is replace the rims and get the money from Chrysler under warranty.

Dear Doctor: I've owned my 1999 Nissan Altima with 124,000 miles since it was new. Last week the speedometer, along with the odometer, stopped working. It will work sporadically. My “check engine” light is already on for an unrelated reason, so I don't know if it triggered a code. In researching the problem, I found that the vehicle speed sensor is a common problem. The part is cheap enough so I replaced it. Nothing changed. Do I have to pull the dash? -- Eric

Dear Eric: The next step is to have a technician connect a professional scan tool and check for fault codes, and then go on a road test to monitor the computer inputs, particularly the signal from the speed sensor. The dash cluster is simple to remove if you need to send it out for repair.

Dear Doctor: I drive in Maine in the cold, snowy weather. How can I keep the rubber seals on the doors from freezing and sticking to the car body during the long cold winter? -- Harry

Dear Harry: You can spray any lubricant that has silicone to coat the rubber. I use the Pledge lemon spray that my wife has in the kitchen cabinet. I also use Pledge as a cleaner on the plastic and vinyl in the interior.

Dear Doctor: I own a 2008 Honda Civic coupe and am interested in the new 2012 Civic Si coupe. I have heard the quality on the new Civic is not as good as the older ones. I saw the new Si and really like it. Do you have an opinion on this criticism? -- Jake

Dear Jake: I spent a week in a 2012 Civic Si with the six-speed manual transmission and I was very impressed with the car in every detail, starting with the smooth exterior bodylines and flawless paint quality. The interior alloy pedals and short throw-shifter are attractive and fun to operate and the sound system with its 360-watt output is an added plus. After my first trip I had to open the hood and see if it had a factory open-air filter.

The engine has a powerful sound under hard acceleration and is rated at 201 horsepower, and in this light car there is more power than you will ever need. Gas mileage is 22 city and 31 highway. The seating is firm and the driver's seat is manual multi-adjustable. The car was fun to drive and after my one-hour work commute each way, I could exit the car refreshed with no back pain.

Dear Doctor: I live in the Snow Belt and as winter approaches I am considering purchasing a compact all-wheel-drive car, such as a Subaru Impreza. I have never owned a Subaru and value your opinion. What should I look for on this car? -- Mary

Dear Mary: Subaru has been around for a long time and is a very popular brand in snowy regions. Over the years there have been many improvements. The early years of Subaru cars were not so good, as there were a lot of cylinder head and head gasket failures, not to mention the failing catalytic converters and rattling exhaust heat shields. With all this said, I spent a week in a new Impreza and what a pleasant surprise with the updated design on both the interior and exterior.

The new 2.0-liter engine now is quiet and makes no more tin-can sound. The engine delivers plenty of power via an updated CVT automatic transmission. Fuel mileage is 27 city, 36 highway. Our test car had the $2,000 all-weather package that also includes alloy wheels and a moonroof. -- Junior Damato, Motor Matters

Junior Damato is an ASE-certified Master Technician. Email questions to info@motormatters.biz Mail questions to: Auto Doctor, 3 Court Circle, Lakeville, Mass., 02347