AUTO: The Motor Medics Help You Diagnose Your Car Problems!

Listen to “Under the Hood” every Saturday at 10AM on Radio for Your Neighborhood – AM 1380 / FM 103.7… WTYM!

Dear Motor Medics,
I’ve been a longtime fan and have used your advice to keep my vehicles in top shape for many years. I try to follow all of the severe service intervals listed in my owner’s manual as you suggest but I feel I may be overworking the severe service times listed. I tow a heavy trailer every weekend in the summer and several times in the winter as well. My tow vehicle is a 2000 Chevy Silverado 4×4 half ton with 190,000 and I’m concerned about the differential fluids. How often should they be changed with the added towing load?
Devin in Wray Colorado

Dear Devin,
Following the severe service intervals is a great place to start if you are concerned about longevity of vehicle components. There are some cases such as yours where we would recommend even more frequent changing of some fluids or at least checking their condition more often. The rear differential is going to be immersed in the water every time you back the vehicle in and because of this reason you need to check it more often for water intrusion which can damage the rear end. Front differentials don’t get used as much under load when not in 4-wheel drive but can also be subject to moisture intrusion. When used in water such as your case we would recommend checking the condition of both the differentials at each oil change which should only take a couple minutes.
Take care, the Motor Medics

Dear Motor Medics,
I have recently purchased my first all-wheel drive vehicle which is a 1999 Audi A6 Quattro. I have owned several 4×4 trucks but never an all-wheel drive car. My last vehicle was a Jeep that was all wheel drive and it still had a lever to change from low to high range. I can’t seem to find any knob or lever or reference to one in the Audi. Do all-wheel drive cars have such things? Is there anything I need to do to make it operate? What about service? Is there something more I need to do being that it is all-wheel drive? I value your opinions which have greatly helped me I the past.
Tina in Dumas Texas

Dear Tina,
All-wheel drive cars have been around for quite some time and most have never had a choice of range selection. A few have them but in most cases such as yours the system is fully automatic and to operate it you simply need to drive the car as you normally would and when the system senses a slipping condition will engage both the front and rear driving wheels to gain traction. This is done either by means of electric clutches or viscous fluid couplings on most vehicles. The electric version uses sensors while the viscous version locks up by means of fluid in the clutches when a slip is sensed. As for maintenance, follow the severe service recommendations in the manual.
Take care, the Motor Medics