Auto Doctor: Losing coolant with no sign of leak

Dear Doctor: I own a 2006 BMW X3. Every six weeks the coolant light comes on and I need to add 16 ounces of coolant. I cannot see any leakage in the engine compartment, nor is there ever any coolant in the driveway. I am baffled. BMW has checked the system and says there are no leaks. Any thoughts? -- Andy

Dear Andy: An engine that is losing coolant with no signs of leaks indicates the engine is digesting the antifreeze. The antifreeze is entering the engine via a leaking head gasket or cylinder head, intake gasket or even a leaky throttle body. Though some of my readers will not agree with this, I have used a bottle of head gasket sealant in many of makes and models, including the BMW X3, with great success.

Dear Doctor: I own a 2005 Ford Taurus. The airbag light on the dashboard is flashing a code indicating "B2293 Restraint System Airbag Status (Driver Front Airbag) Circuit Failure." The turn signal lever stopped automatically kicking back to the off position after completing turns a long time ago. Do you think these two problems are related? -- Michael

Dear Michael: When it comes to airbags, which are safety items, I recommend an inspection by a qualified technician using the proper test equipment. I have seen many false airbag deployments from untrained mechanics probing into wires for testing. Clock springs are a common problem, as are crash sensors and poor corroded connections.

Dear Doctor: I just purchased a new 2012 Chevy Silverado 4WD V-8 with the flex fuel feature. Can I mix E85 with regular 87 octane gasoline -- say half and half for around town driving? Would using 87 octane for highway driving give me better mileage? There is currently an $.80 difference in price. -- Laurie

Dear Laurie: I own GM pickup truck with the flex fuel feature. I do not recommend the mixture of a 50/50 blend of the two fuels. I suggest using one or the other. As for the better gas mileage, you have to run your own checks, which depend on your driving and hauling.

Dear Doctor: I have been the lecture teacher of Driver Education at several high schools for the past 11 years. Over 3,900 students have gone through my classes and successfully passed their road tests. I'm one of the few driving instructors who teach outside the box. Can you recommend anything to get the future drivers better prepared? -- Carl

Dear Carl: An overlooked area of needed training is basic car maintenance: how to check simple things like fluids under the hood, how to change the spare tire if equipped, the proper way jump-start a dead battery, and to not run the fuel below a quarter tank.

Dear Doctor: I'm in the market for a new car and am considering the Dodge Dart. Have you driven it? -- JC

Dear JC: Yes, I drove the new Dodge Dart, and this is not the old 225 slant six made in Detroit. This is a front-wheel-drive car that seats four and comes in a few different models. Our test car was the SXT 2.0-liter four-cylinder with 160 horsepower and the 6-speed manual transmission. The car drove very smooth and the manual transmission gear ratio kept the engine at the proper rpm range and the clutch pedal was very easy to depress. If the 2.0-liter had more power the Dart would be the perfect small sedan. There is a 1.4-liter turbo option available. You need to drive both and make your choice. -- Junior Damato, Motor Matters

Junior Damato is an ASE-certified Master Technician. Email questions to info@motormatters.biz