'Brand new' cars, oil weights, foamy transmission fluid

By John Paul, AAA Car Doctor
September 18, 2008

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Q. Today my wife and I bought a new Nissan Sentra from a local Nissan dealer in Massachusetts. When my wife signed the odometer document, it listed 25 miles. We drove off the lot and drove about five miles when she noticed the odometer read about 225 miles. My guess is the car had been a "test drive" car. Can you outline our options?

A. The car is still considered "brand" new – although I think you have the right to be ticked-off with the dealer for not being completely honest about the mileage on your car. The reality is 225 miles isn't very many and could be a result of the car being driven from one dealership to another. Many times dealers will trade cars with one another, to satisfy customers' color and option choices.

Q. I recently changed my oil and filter, and after the job was done I discovered that the repairman used 5W-30 weight oil. The specifications for my car, a 2006 Ford Fusion with a V6 engine, state that the motor oil should be 5W-20. Would this higher weight oil cause a problem? If so, should I immediately change it to the correct weight, or can I wait until the next oil change?

A. Most vehicle manufacturers recommend a range of oil based on the driving conditions of the vehicle. Some will recommend 5W-20 as all-weather oil with, as an example, 10W-30 if the vehicle is driven in conditions above 32 degrees. Ford, unlike some other manufacturers, is very specific about the oil that is used in its vehicles. The recommendation from Ford is 5W-20 oil that meets the Ford WSS-M2C930-A specification. Since the 5W-30 oil doesn't meet this specification, I would return to the repair shop and ask to have the correct oil installed in your car's engine.

Q. I have a "check engine" light that came on and disappeared a day or two later. Since then, it comes on once a week or so. The car is a 10-year-old Chevrolet that I tend to work on myself. The local garage wants $75 just to tell me what the engine code is. He said he needs to charge this amount, since his scanner costs over $4,000. With my older Chevy, I could use a paper clip and count the check engine light flashes. Is there an economical way around this?

A. Some garages and auto parts stores will perform a complementary "code" scan. If you want to read the code yourself, there are several inexpensive code scanners on the market. Black and Decker recently sent me a code reader called SmartScan. It is pretty interesting since it rates the code on severity, and in terms of how soon the particular problem needs attention. The retail cost is under $80.

Q. I have a 1997 Honda Accord, and the transmission is slipping. It's an automatic transmission, so when I checked the fluid level it was foamy. What could be the cause of that?

A. Generally fluid will foam when it is over-full, or the transmission pump could have started to fail. It is also possible that the transmission cooler (part of the radiator) has failed and is coolant mixing with the transmission fluid. The antifreeze will have a slightly oily appearance. As good as Honda products are, Accords have not had the best record when it comes to transmission longevity.

John Paul is the public affairs manager for AAA Southern New England. He can be reached at


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