Automania/Repair & Maintenance

AUTO QUESTIONS AND ANSWERS FOR WEEK 30 YEAR 2000

by Bob Hagin

Q. I have a '97 Toyota 4Runner, SR5, 4-wheel drive, automatic transmission, V6 engine and 24,000 miles. As you know, most 4-wheel drives are really 2-wheel drive - one front and one rear. Last time I was in the snow, I was sort of left high and dry with the left front and the right rear spinning. A locking differential or limited slip rear end is one of those "options" that are not available on a 4Runner unless you buy the most expensive (Limited) model. Is it feasible to put in either a differential lock or a limited slip as an aftermarket product or by using original equipment Toyota parts? D.B. Chico, CA

A. Aftermarket performance equipment for the 4Runner and the Toyota pickups is readily available. I'm told that one of the strongest and most easily installed is made by Powertrax (www.powertrax.com) and that they make them for both front and rear differentials. Most major areas have shops that specialize in off-road equipment and repairs but you have to dig for them. The only problem you might run into is that installing one might negate some part of your warranty or warranties. An original equipment system should be no problem, but expensive and not all Toyota dealership shops are keen on doing "specialty" work. You can try Toyota Racing Development (TRD) at www.trdusa.com. While the limited slip differential wasn't an option on the SR5 in '97, it is available on the '00 model as part of a special sport package. Usually this means that one can be retrofitted to a slightly older model.

Q. I am concerned about changing my oil. I bought a lifetime oil change program for my 1996 Ford Escort when I bought it new. Since I've retired, I only put 100 miles on my car each month. Ford told me that they would not change my oil until I get 23,5090 miles on it which would take around two years at the rate I drive now. They told me to go out and drive more. I though that the oil changes would be done every three months regardless of the number of miles I drive. S.C. Kent, WA

A. Oil doesn't wear out but in an engine, oil becomes contaminated with the by-products of combustion and if you don't drive your Ford often enough to get the oil hot enough to burn off these contaminants, they'll affect engine bearings and piston rings. The alternative is to change your oil and oil filter more often or drive it harder and more frequently. If you plan to keep the car, but don't want to do more driving, the alternative is to change it more often and pay for it. Unfortunately, I don't know of a simple "litmus test" for motor oil contaminants that can be done at home.

Q. I have a '94 Ford Explorer four-door, two-wheel drive Eddie Bauer. At 65 to 75 mph, it feels like all my wheels are out of balance. The tires are not the originals but are of the same size. I didn't notice the vibration until about 66,000 miles, when the new tires had gone 10,000 miles. I had five different tire shop balance them and they were only a little out. Ford replaced the rear pinion seal at 70,000 miles but said the bearings were OK. On the internet, I found that new motor mounts, another set of shocks and a rear axle damper may or may not fix it for $900 excluding labor. By law, wheel balancing is limited to 55 mph. J.H. Chesapeake, VA

A. Ford has always depended on add-on vibration dampers on transmissions and rear ends so the kit may be your only cure but first pull the oil from the differential, save it and inspect for ferrous "bits" using a magnet. "Burnelled" pinion bearings caused by incorrect preload can cause a vibration like you describe and so can an out-of-balance or a misaligned drive shaft.